Undertale Yellow

Clover falls into the Ruins and meets Toriel. She briefly guides them, but when they pull the second lever in the lever puzzle, they fall into the Dark Ruins. Clover loses the Missing Poster in the fall. In the next room, they meet Flowey, who introduces them to the mechanics of dodging and saving. From there, they traverse the Ruins with Flowey in a peaceful manner, sparing every monster along the way and solving the puzzles. Eventually, they battle Dalv at the end of the Dark Ruins. While Dalv initially mistakes them for Integrity, another human due to their resemblance, he realizes that Clover isn't there to harm him and Clover becomes friends with him, which motivates him to leave the Dark Ruins. Dalv escorts Clover to the exit of the Dark Ruins.

After leaving the Dark Ruins, Clover ends up in Snowdin. They run into Martlet fixing a puzzle, but she does not see them. Clover explores Snowdin, meeting a variety of monsters and finding the Honeydew Resort, but Clover soon encounters Martlet once again at her lookout station. She realizes they are a human, which results in a battle. Clover can either refuse to attack her or alternate attacking and sparing her. Either way, she will end the battle and offer to guide them back to the surface. Together, they board the UG Aviator and ride through Waterfall. Unfortunately, instead of docking, the boat speeds up and crashes into the Dunes.

As a result, Clover becomes separated from Martlet, which Flowey expresses relief about. Clover traverses through its dangers of the Dunes for some time, exploring the East Mines, meeting El Bailador, and sparing monsters. After a while, Martlet catches up with them once more. She follows them along, but this is short-lived.

As soon as they enter the Wild East, Starlo is captivated by seeing a real human. Clover is taken by the Feisty Five to be trained to join their crew and Martlet is put into jail to keep her out of the way. During Clover's training, they get the Nice Hat, as well as the Wild Revolver after Starlo buys it for them from Blackjack. Starlo prioritizes Clover over the feelings of his posse during this time. After promoting Clover to deputy, the Feisty Four battle Clover and tell Starlo off. Starlo blames Clover for their argument and fights them. They refuse to fight him, instead waiting it out until Ceroba arrives to talk him down. Afterwards, Martlet approaches Clover, now free, and informs them of her departure to Snowdin.

After Martlet exits, Clover comes to the Steamworks gate where Ceroba and Starlo wait. Ceroba explains her daughter Kanako's disappearance to Clover. She tells them Kanako is in a Lab, and she is going to seek her out. She asks Clover to accompany her while Starlo stays back to watch the town. Now teamed up, Clover and Ceroba traverse the Steamworks. After turning on the power, they meet Axis, who was created by Chujin Ketsukane, Ceroba's husband. As he perceives the duo as breaking in, they are forced to avoid him on multiple occasions. They solve various puzzles and encounter many robots while learning about Ceroba and her family's past. At the exit, Axis manages to corner Clover, resulting in a conflict where Ceroba is locked out of the room. Clover slowly drains Axis's battery while Ceroba tries to break in to the room. After she succeeds, Clover drains almost all of Axis's battery and he calms down. Ceroba presents the machine Clover made at the beginning of the Steamworks. Axis immediately falls in love. Before Axis takes the machine away, he whitelists Ceroba and Clover to prevent him from attacking them again. After beating Axis, Clover and Ceroba make their way to the elevator at the end of Steamworks. However, Starlo interrupts to confront Ceroba about items he found within her house and Clover is taken back to the Wild East by Ed.

There, Clover reunites with Martlet and the Feisty Four reveal to Clover that Ceroba had ulterior motives the whole time. Martlet and Clover go off to investigate her home. There they find a secret room underneath her kotatsu containing tapes made by Chujin, who had been working to create a special serum extracted from a monster injected with a human SOUL extract in order to make monsters stronger and protect against humans.

After finding Ceroba's secret, Martlet goes to New Home and Clover has time to visit past locations. When they are done, they meet back up with Martlet on the UG Apartments rooftop and head into New Home to search for Ceroba. They find Starlo in the middle of an argument with her. The situation quickly escalates and Starlo tells Martlet to escape with Clover. Ceroba reacts quickly and attacks Martlet and Starlo, monologuing briefly before initiating a fight with Clover. Clover gains the ability to shoot and dash in her fight. After doing enough damage with their SOUL, they can see her memories highlighting secrets from her past. After defeating Ceroba, Clover has a choice of either sparing her or killing her.

If Clover chooses to spare Ceroba, both Starlo and Martlet wake up and try to plan for the future with Ceroba. They start to argue as they cannot figure out a way for Clover to live safely. Slowly, Clover realizes both that they are unable to leave the Underground and that monsterkind deserves to be free. They insist on giving up their SOUL, despite the protests of their friends. They hand Martlet their hat and Starlo their gun, and the two leave, unable to watch, before Clover takes out their SOUL and gives it to Ceroba. Ceroba asks if she should stay, but they tell her to leave. Flowey expresses disappointment at their choice to give up their SOUL, but says farewell one last time as they pass away.

If Clover chooses to kill Ceroba, Starlo expresses fury at them while Martlet defends their choice. He leaves, and she takes Clover to Asgore. Once facing Asgore, Clover asks for Martlet to leave, which she reluctantly does, and Asgore takes Clover to the Barrier. When he reveals the five souls, Clover trembles and aims their gun at him. Asgore initiates battle, starting an attack that does not end, and Clover's SOUL is eventually captured.

Dalv's text changes in the Neutral Route depending on how many enemies you have killed. And unlike in Pacifist, he will choose not to pack up and move to Snowdin but rather stay in the Dark Ruins and connect more with the residents there.

If Dalv is killed, entering his room will allow you to play his Organ Demo. This is only available on the Neutral route, as it is silent on the Genocide route.

If Martlet is defeated by depleting her HP, she will retreat, which leaves Clover travelling on the raft alone.

El Bailador is not aware that the player is fighting him, unless they decide to kill him. Also, even if you killed enemies before you meet Mo, he won't notice that the player killed the monsters so Mo does not reveal that he has committed tax evasion. El Bailador is not aware that the player is fighting him, unless they decide to kill him. Also, even if you killed enemies before you meet Mo, he won't notice that the player killed the monsters so Mo does not reveal that he has committed tax evasion.

Ceroba will not follow Clover into Steamworks as she tries to find Starlo, leaving Flowey as their companion instead.

After receiving Starlo's letter in the Steamworks, backtracking to the Saloon in the Wild East unlocks a neutral-exclusive scene. The Feisty Five, along with Ceroba and Dina, are celebrating the posse's reunion, with Moray performing a song for them on the stage. When talking to Starlo, he mentions that Moray is performing a set, but that they've been on that particular song for awhile. This is likely poking fun at how the song will keep playing until the player exits the Saloon.

If you kill Starlo during his fight, Ceroba will question where he has gone as she is unaware that you have killed him and will go to his family in hopes of finding an answer. If you enter Starlo's house up ahead, a neutral-exclusive scene will play where Starlo's family will mention that they can't find Starlo anywhere even in his room and speculate as to where he could have gotten. Ceroba then encourages a bigger search to go on as they haven't exhausted their options yet and she will leave the house without saying anything to Clover, and she is never seen in game from that point again.

If you backtrack to the Wild East, Mooch will be infront of the Feisty Four's house and wonder where Starlo is.

Most of the first section of the Steamworks is unchanged from Pacifist minus many cutscenes that would have had Ceroba, the scenes with Axis are also a bit different as they are shorter with only Clover. Once you fall in detainment, Flowey catches you and you have to use the vent to escape, you don't build a robot like in Pacifist. Everything is the same as pacifist until you reach the Axis chase where he will only hunt you down and when you finish the first part of it, you are not required to go in a locker like in Pacifist. At the end of chase cutscene, Flowey will save you by shooting a bullet at Axis before he blasts Clover, and it destroys his arms like in Pacifist.

For the second section of the Steamworks, instead of taking the left door on the fork, Flowey breaks down the upper door, unlocking a different route. The player is required to make a Steamworks ID to get past this point, which is exclusive to the Neutral Route and if you go back to the vending machine, they will have vastly different nicer dialogue as a result of you having a Steamworks ID.

Though the kitchen/lab area is also accessible on a Genocide Route, you can only obtain the Cake item within it on the Neutral Route. Also unlike Genocide, using the Hydrochloric Acid on the locked door will initiate a cutscene with Axis, who has his own vial of acid. After struggling to open it, he drops and breaks the vial which burns a hole directly beneath him. This causes him to fall through the floor.

If the player chooses to spare Axis, instead of the player-created machine filling Axis with emotions, Clover compliments him until he repairs himself and leaves. Axis can later be found recharging next to the opened cabinet near the start of the Steamworks as an NPC.

Alternatively, if the Pacifist Route is aborted by killing any monster other than Guardener or Axis, Steamworks will have the same trajectory as the Pacifist Route, until the end where Ceroba abandons you due to "Clover's soul not being pure".

Upon reaching Hotland, Clover will find a letter from Martlet, asking them to meet her on the UG rooftops to discuss Clover's future.

Flowey interrupts Clover's walk to the rooftop, informing them this isn't the way to the castle, asking them to turn back and continue the plan. When Clover ignores him, he says the letter from the Steamworks is likely a trap and asks if they're so dumb as to fall for that, saying that bird never got them anywhere, but eventually gives in and lets them meet with her.

Instead of having called Clover to the roof to stop Ceroba or Clover themselves, Martlet wanted to talk to them. The dialogue here depends on if Clover aborted a genocide run or not, and how much LOVE/EXP you have on a neutral route
If the Genocide Route was never attempted, and depending on your LOVE/EXP, Martlet remarks that New Home is on the other side of the CORE, but then talks about the fact that she was told that all humans are the enemy. She comments that maybe those people were right, and she had a plan to stop Clover if need be, which she throws away. Her general dialogue will differ with her being more skeptical and worried for you the higher your LOVE is and more sympathetic and kinder the lower your LOVE is. She tells Clover she knows they're good deep down, but that they could never get past ASGORE as he wouldn't hesitate to take their soul.
If the Genocide Route has been aborted, Martlet cuts straight to her being told humans are the enemy with a less cheery voice, as she realizes they were right. Yet, she senses better in them. She still shows her plan to stop Clover and throws it away. She offers for them to shoot her now if they're going to do it anyway, saving they'll never get past ASGORE, though Clover does not fire a bullet.
And depending on your LOVE/EXP her general dialogue will differ with her being more skeptical and worried for you the higher your LOVE is and more sympathetic and kinder the lower your LOVE is.

Either way, she offers for Clover to live with her in a "happy, violence-free childhood", believing they can change for the better and end the conflict, which Clover either agrees to, or stays silent about, with dialogue choices that change based on your LOVE. Both options lead to Martlet preparing to take Clover to Snowdin before being impaled by a vine sent by Flowey. She assumes it was Clover and either asks why, or says she should have known before dying, prompting Flowey to face Clover.
If the Genocide Route was aborted, Flowey taunts them that he got to her first, before realizing Clover was actually going to stay with her. He mockingly asks if they were trying to turn this around after what they did to the Underground and says there was no redemption for their actions. He does thanks them for turning it around anyway so he could betray them before they became too powerful.
If it wasn't attempted, Flowey gets annoyed, knowing something like this would happen, that he tried to have a friendly persona but finally reached his limit. He then confesses it felt good to finally snap and kill Martlet when she didn't see it coming, and loves the fact her last thoughts were Clover betraying her. He then kills Clover and takes their soul, though Clover still holds on to their sense of self. He talks to them, reminding them about their simple plan to go to ASGORE, and that they've always been predictable. He then reveals this run is in the hundreds as any other run, Clover either stayed with Toriel, or died outside the Ruins. So to steer them off that path, Flowey tampered with the switches to bring them to the Dark Ruins. He then grows surprised Clover is still here, thinking they would have given up after his boring story, but then fights them. If you already did Neutral once, Flowey will skip the monologue and it will transition straight to the fight.

After the fight, Flowey calls them annoying for not giving up and lying down, though he admits it was fun for a moment. Flowey decides to "cut a deal" and reset the timeline back to when Clover first fell down, though he may try to take their soul again if they end up in the same scenario, and advises them to make different choices, as "this outcome sucks" and this isn't what he's truly looking for.

If you reach the Neutral ending a second time, Flowey apologizes for the fight not being as "flashy" as before as he goes on to state that despite wiping Clover's memory clean, the human is somehow getting better at trekking through the Underground, and state he'll keep resetting until Clover gets him the SOULs.
If you reach the Neutral ending a third time, Flowey expresses confusion as to why no matter what happens, Clover will always be convinced by Martlet to stay with her. Believing that Clover's "fate" is locked in and must play out in a certain way, he realizes that they are not the one they need, and plans to abandon his "helpful" act and embrace his sociopathic behavior once he's rid of Clover before resetting, and demands Clover not to mess up again.

Reaching Neutral Route on a four playthrough onwards has him tell Clover if they have anything better to do before resetting.

If FUN is at 70+, then Flowey asks Clover why, despite being alone in his mind, he still feels like he's being watched (implied to be the Anomaly/player). He decides to RESET, to make sure Clover goes on "the right path" and this paranoia go away.

At the start, nothing very relevant happens. Dalv's monologues remain the same, enemy encounters continue triggering, and puzzles still have to be fully solved. However, if the player continues their Genocide Route until they kill 13 Dark Ruins enemies (not counting unique encounters), the normal battle music is replaced with Enemy Retreating along with Flowey's save point dialogue changing to state how many monsters are left until the kill count is exhausted. With each kill, the pitch and speed for Enemy Retreating lower after the battle is over. If the player exhausts the Dark Ruins kill counter before the fight with Decibat would normally play out, the fight is skipped entirely.
Flowey will appear after killing the last monster in the Dark Ruins, saying that Clover "is not for that mercy thing", but reassuring them that he's their friend, saying that real friends don't judge each other. Flowey's dialogue also suggests that Clover briefly thought about killing Flowey before he reminded them that he's the only reason Clover can save. After this, the overworld music will slow down and lower in pitch. Even after Enemy Retreating and Flowey's appearance, Dalv's final monologue before his battle will remain the same.

Even after Enemy Retreating and Flowey's appearance, Dalv's final monologue before his battle will remain the same.
However, when the battle starts, his dialogue will be entirely different. He will mention that he despite his desire to be left alone, that he noticed dust lying all over the Dark Ruins, and that nobody comes to his house anymore. He admits that he wished for everyone to be gone and that he should thank Clover for their actions, only to realize that he now misses the late monsters. Dalv will then mention how he regrets never trying to befriend the monsters in the Dark Ruins and begins to wonder if his wish for them to disappear was somehow granted, making Clover a figment of his imagination, and the entire battle a dream. Upon meeting his death, however, he realizes that Clover is indeed real and that when he wakes up, Clover will still be there. He realizes that it's likely he just won't wake up at all, before dying as he turns to dust. However, if he is spared, he will become extremely angry, saying that Clover only spared him to make him suffer more, and will stay in his room until the player leaves for Snowdin through his house. When Dalv is killed, they will have access to the entire house, including Dalv's previously inaccessible bedroom which includes a journal containing a single entry. The descriptions of the items will be much crueler, and if the wardrobe is opened, Pops's helium will be sucked in by Clover, making them sound funny for a while. Just like in the Neutral Route (if Dalv is dead), Flowey will break the planks for Clover to pass.
If the protagonist spares Dalv, he will retreat to his bedroom without return. The description for the items will be the same as on the Neutral Route, and Flowey will open the door for Clover to pass.

At this point in the run, consumable items will stop having flavor text upon being eaten, and will only display how much HP was healed.
Slurpy's side-quest can't be completed since most of the necessary NPCs have been evacuated.
However, as of version 1.1, if the Dark Ruins kill counter was exhausted and Dalv was spared, the run will return to a Neutral Route, allowing the side quest to be started, but can still go back to a Genocide Route by killing 20 Snowdin monsters afterwards. Do be careful with EXP grinding if you attempt this or you may be underleveled for some boss fights. When the kill counter is exhausted, most of Snowdin's NPCs will be evacuated, with the exception being the band inside Honeydew Resort.
To continue the Genocide Route, you must exhaust the kill counter before attempting to fight Martlet. Martlet's battle is significantly more difficult.
Her AT is higher (8 in Neutral, 12 in Genocide Route) but her DF is lower (10 in Neutral, 8 in Genocide Route).
The bullet patterns closely resemble those of her usual battle, but employ additional projectiles and more rapid attacks.

The only thing changed from the Pacifist/Neutral Route at first is that almost all NPCs have disappeared. The Monster outside the East Mine leaving for Snowdin, the one outside the jammed elevator, and Moray's parents are the only ones you will encounter. The first of these is seemingly off-put by your appearance, being a lot more apologetic after bumping into you, and stammering a little. Moray's parents offer to let you stay in the headquarters, implying that news of you hasn't reached the Dunes yet.
Before the El Bailador fight, there is a conversation with Flowey about how if Clover is excited that they have come this far, the only option being to reply with "...", making Flowey a bit discomforted. He mentions how you're harder to read, and gloomy, before dismissing it and letting you save. The El Bailador fight is changed entirely, with your SOUL being outside the box it was confined in. Instead, you dodge the descending "Note Bars" from inside their box, with free movement, with the notes getting knocked away at the bottom of the box instead. Coupled with the fact El Bailador gets very disheartened halfway through the fight, it makes things much easier than in the Pacifist run of this fight. Though if the kill counter has been exhausted before heading to him, the fight will not happen. If Clover has not killed all enemies before heading into Oasis Valley, a pop-up will appear that says "There are still enemies to bring justice on.", allowing you to turn around and check again.

After this checkpoint, Martlet will approach Clover, pleading with them, and trying to empathize with them. She also mentions that the rest of the Royal Guard are looking for them, and they're lucky it was HER who found them. Twice, they interrupt her. First, by stepping forward, then by pointing their gun at her. This prompts her to leave. On the road approaching the Wild East, the Wild Revolver will be sitting on the ground. Upon taking it, it will be equipped and the Toy Gun will be thrown away automatically. Upon entering the Wild East area, Starlo approaches Clover, trying to settle things with a clean, moral duel. However, in this duel, contrary to the Pacifist Route, the player may prompt Clover to fire at any time. Regardless of if you try to fire or not, Starlo will end up shot, with Ceroba approaching him to comfort him. Afterwards, a fight with her will occur. This will prove difficult, as both phases of her fight have attacks that will temporarily reduce your Max HP for the rest of the fight. Dodging red-colored attacks will be key to avoiding that, and refraining from touching the walls of the battle box will become necessary in Phase 2 of the fight.

Clover quickly shoots the panel to unlock the Steamworks gate while Flowey is talking.
Clover tries to shoot the generator, which upsets Flowey, prompting him to state that bullets aren't always the answer to their problems. Clover quickly strongarms Flowey into breaking down the door instead, skipping two puzzles.
Most of Clover and Axis's encounters have them switch places in contrast to the Pacifist/Neutral Route. Axis tries to attack Clover during their first encounter due to their vandalism, which results in Clover swiftly shooting off the left side of Axis's face. Axis makes his escape through the trapdoor, saying that he must evacuate the others.
During their second encounter, Axis flees while Clover pursues him instead. Axis is then absent from the long hallway afterwards.
Axis is absent from the third encounter - after Clover uses the Hydrochloric Acid.
Axis's boss fight has Axis wielding the trash can lid instead. Clover treats Flowey a lot more coldly after this point, commanding him to move things for them, and even walking threateningly towards him.
Macro Froggit will not come out of the door and fight Clover if the unlock requirements are met. Instead, a Micro Froggit will toss out the chest with the Golden Bandana and leave.
You cannot purchase items from Mo, as Clover instantly points their gun at him when he tries to speak. You can then choose to rob him of his hundreds of G or not. This is optional to the Genocide Route.
Seeing as the player will likely have a lot of G at this point, and considering how G is never truly relevant in Genocide, there's never really any reason to rob Mo.
Clover being unwilling to kill Mo can also be interpreted as Clover, even on this route, having a "code" of honor, only ever attacking monsters who attack them or don't surrender. This claim can be backed up with Clover letting Martlet escape twice (even when it turns to their detriment in the long run).

Vendy hasn't fled since they are a stationary machine, but much like the other vendors, it will still give you all its items for free, like any other vendor in the Route.
Approaching Guardener will play a cutscene where Axis reassures Guardener and tells her to stay hidden. Guardener then spots Clover and quickly hides.
If Clover has not yet killed all robots by the time you reach the computer room preceding Axis, you will abort the Genocide Route, and this is the last point at which you can do this.
Axis takes the trash can lid during their boss battle instead of Clover. He cannot be damaged during this fight as he blocks all attacks and all Clover's attacks deal 0 damage. Because of this, Glass Bullets will not heal you upon hit. After finishing the final attack, Axis will attempt to explain and apologize to Clover, as his protocol forced him to kill one of the fallen humans. At this point, all health will be restored, and Clover will rapidly level to LV 19, SOUL turning upside down to fire a bullet at the trash lid, blowing it away before firing again, destroying Axis.
It is recommended to only use healing items that heal less than 20 or 30 HP on this fight since they will be needed later.

When Clover enters Bits and Bites, the normal shopkeep is not present. However, a strange figure can be seen in the background.
Clover meets with Martlet on the rooftop. In a desperate attempt to stop Clover, she injects herself with the determination syringe and transforms into her "Zenith of all Monsterkind" form, engaging Clover in a two-phase fight.
Clover will be fully healed upon entering the second phase. Once Martlet has been killed, Clover's LV reaches 20. With more determination than Flowey, Clover easily foils Flowey's attempts to sabotage their plans or escape. Flowey resorts to taunting Clover, before they ultimately shoot Flowey to death.
Following this, Clover travels to the Castle, encountering Asgore. After speaking to Clover of the consequences of their actions, he attempts to destroy Clover's SOUL with his trident, only for the weapon to be shattered upon impact. Clover then vaporizes Asgore with a laser beam emitting from their SOUL. They then absorb Asgore's SOUL, collect the five other human SOULs, and proceed to exit the Underground.

The player can abort the Genocide Route if they reach certain points without exhausting the kill count or by sparing bosses. For example, if the protagonist spares Decibat and then goes back to exhaust the kill count, Enemy Retreating still plays, the cutscene where Flowey tells Clover that friends don't judge each other and the music slowing down still occurs despite the Genocide Route being aborted.

Dalv has unique dialogue in his battle if the Genocide Route is aborted, however it can only be seen if the protagonist repeatedly spares him as his dialogue when being fought is the same as in the Neutral Route.
Unlike the Neutral and True Pacifist routes, Dalv does not let the protagonist shake his hand.
The hangout does not occur as Dalv states that he feels ill and proceeds to his room much like if spared on the Genocide Route, albeit on better terms, and the protagonist hears an organ playing on the other side when checking the door to Dalv's room.

If you apologize repeatedly to Martlet at the beginning of her boss fight, the option will turn yellow, allowing you to abort the Genocide Route there as you do not force Martlet to retreat by depleting her HP.

If you try to proceed to Martlet's second encounter before exhausting the kill counter, a pop-up will appear that says "There are still enemies to bring justice on.", allowing you to turn around and check again or continue. If you choose continue, the route is aborted.
It is impossible to spare Ceroba to end the genocide route during her boss fight.
Her name will turn yellow when she is one hit away from death, but this just means she is close to dying, not that you can spare her.

Entering the control room just after the laboratory will disable any future encounters. If you fail to exhaust the kill counter beforehand, Clover can either kill or spare Axis at the end of the fight when the latter drops the trash can lid and rests. Even if you kill him, the genocide route is aborted at this point. If he is spared, he will say that letting him go is a weird decision. Before leaving, he will tell Clover "Y0U STILL [freaking] SUCK" and wish for them to trip and fall to their death.
If you abort the Genocide run here, Ceroba will appear in the neutral finale.

Clover is the playable character and main protagonist of Undertale Yellow. They are the seventh human to fall into the Underground and the sixth SOUL gathered by Asgore Dreemurr in the Pacifist endings. Embarking on a quest to locate the previous five humans who climbed up Mt. Ebott and were never seen again, Clover ventures into the Underground. Clover is a human child of fair complexion and short brown hair. Official art portrays Clover with yellow irises.

Clover wears a brown long-sleeved t-shirt beneath a dark brown vest and dark blue pants, presumably denim, girded by a dark reddish-brown belt with a gold buckle. They wear a pair of brown shoes and a light brown cowboy hat with a dark brown hatband. Around their neck, Clover sports a yellow bandana with a blue dot pattern. Clover's background is left ambiguous; however, they were most likely an honest child. This is proven when their main reason for jumping into the Underground was for the five humans preceding them. While never explicitly stated, it is implied that Clover may have an abusive or overly demanding family, this may have resulted in them becoming independent at a young age. It's also possible that Clover is somehow used to arguments and prefers to resolve conflict, as shown at the end of the Pacifist Route where Clover seems to be trying to drown out the argument between Martlet, Ceroba, and Starlo and ultimately gives up their SOUL to resolve it.

Flowey is a sentient golden flower with six yellow petals, a white androecium, and a light-green stem. He can make a variety of facial expressions. Flowey is nice to Clover and helps them, following them once they fell in the Dark Ruins. As Clover seemingly doesn't have enough determination like Frisk, Flowey owns their save file and saves the game for Clover. Flowey is also focused on getting you to Asgore, not wanting to bother with anyone else, as it disturbs his true goals of acquiring the human souls for himself.

At the end of the Genocide Route, Flowey finally snaps at Clover for aiming to kill him and reveals that he actually always hated them, and only kept reviving them so he could gain satisfaction from watching them suffer over and over again.
After Clover falls into the Dark Ruins, they run into Flowey, who after a tutorial on how to dodge attacks, promises to help them in their quest to reach Asgore and rescue the five missing children. From there on, Flowey use his SAVE to keep Clover from dying for too long, and reminding them of their goal. However, he gets annoyed if you keep saving at the same spot for a while, and never shows his face should Clover have anyone following them.

Dalv is a humanoid monster with a purple complexion, fangs, and horns. He wears a dark purple cloak with a hood that conceals his face. Excluding his horns, his appearance is similar to, if not based on, that of a vampire. He also wears a white medieval shirt beneath his cloak, as revealed in his overworld sprite if Clover spares him in a True Pacifist or Neutral Route. Dalv is socially awkward and claims to desire solitude. He often monologues about how he sent the other monsters away and how he wonders if they ever really cared about him, and is consistently interrupted by Clover. Despite that, he later reveals that he does not actually want to be alone, but rather fears that any friends he makes will leave him behind the moment they grow tired of the Dark Ruins. When hanging out with Clover, he seems very happy to have a friend to talk to. His interests include writing and illustrating children's books, playing the organ and growing vegetables (especially corn). While it is never stated directly, it can be inferred that Dalv was friends with Kanako Ketsukane prior to the events of the game from the portrait of Dalv that can be found in Kanako's bedroom.

In the secret tape (found behind Chujin's gravestone), it is revealed that Kanako was in Snowdin with an unnamed monster (most likely Dalv, based on other clues) when they were attacked by a human. Though Kanako was unharmed, Dalv specifically was injured in the attack.[1][2][3] Additionally, from the "Is this some sort of haunting?" remark, it can be inferred that Dalv is aware of the death of the human in question (either through directly witnessing Axis terminate them or being told the news after it occurred).

After the incident, Dalv moved to live in the Ruins in self-imposed isolation. Chujin (potentially during his time with Martlet) began leaving cobs on corn at Dalv's doorstep (perhaps out of sympathy or a request from Kanako).

Martlet is a blue anthropomorphic bird-like monster with two wings used as arms. She wears two yellow-ochre snow boots. She has a mop of hair on top of her head with outsticking parts and a feather-like tuft near the back. She wears a greyish blue sleeveless shirt and dark blue pants.

When Martlet transforms with her serum, her eyes turn a glowing yellow, and her hair, wings, and legs become longer. Her hair drapes down more and is more wavy. She sports a breastplate with a heart design in the middle and shoulder pads fitted into the suit pointing up. Her boots disappear from her original design, with talons replacing them. Martlet's hair is also more elegantly displayed, with the outsticking motif from her original hair style being accentuated. Martlet is shown to be, as the game states, scatterbrained. Martlet seems to struggle with concentrating on her duties and often relies on a manual or lists so she can know what she has to do. Her laziness is also hinted at in the game with a note on Information booth that tells passerby to wake her up if she dozes off on the job.

While she seems a bit naive on the surface, what Martlet makes up for in her disorganized workflow is her strong morale. As shown in the Genocide Route, Martlet has a strong sense of justice, and is more serious compared to her Pacifist counterpart. She even runs away from her initial battle via a tactical retreat, and monitors Clover for most of the game. She will go to great lengths to put a stop to anyone trying to harm monsterkind, including injecting herself with a fabricated serum, just so she can have the power to put an end to Clover’s killing spree, no matter the cost.

Starlo is a humanoid monster. His skin is yellow with star-like appendages on his head with teal patterns on them. He wears a brown poncho with teal stripes with his sheriff badge on it; a dark brown ten-gallon hat; brown pants, and black boots with spurs. Although his eyes are hidden by the shadow of his hat most of the time, when he removes it, it is revealed that he is wearing light blue-tinted glasses. Starlo also wields a silver revolver. Starlo's true personality is superseded most of the time by a western persona. Borne out of a fanaticism of Wild Western culture, Starlo puts on this persona from a desire to spread excitement and drama to the inhabitants of the Underground - distracting them from the cruel reality of monsterkind's collective banishment from the Surface. Going by the moniker of "North Star," he plays the role of the Wild East's upbeat sheriff, who is determined to "keep the peace" by any means necessary. This for the most part is all drama, as there is no real danger (besides potentially Clover) and is all put on as a fun distraction for the Dunes' inhabitants, who all seem to play along. Starlo's true personality is revealed after his boss fight in the Pacifist Route. He is shown to be much more of a nerd - a picture in his home revealing he at one point was even adorned with stereotypical dweeb braces. As such, his room is filled with various Western memorabilia from the Surface and even contains glowy sticker stars. Despite this, however, one thing that is constant between "North Star" and Starlo is his kindness and how he values those close to him. In fact, this is the whole reason the "North Star" persona exists in the first place.

Ceroba is a humanoid fox-like monster with beige fur and long, wavy ginger hair. Her hair is tied up in a ponytail by a red ribbon with a small gold bell in the center. She has a long, white kimono with red trimmings; a red obi sash tied around her waist and white boots.

During her battle phases, she carries a long red staff with a bright yellow bell at the end two little red ribbons tied around the ends of the bell. In the Pacifist Route battle, she wears the Kitsune mask made by Kanako, consisting of two dark eye sockets that receive bright red dots in the final phase, with pink dyes. Her hair becomes more voluminous, resembling tails with pink shine. Additionally, she wears a cloak that is shown in concept art to be yellowish-white with pink edges.

Her attacks in the overworld are represented as white and pink flashes of light. Brilliant and skeptical, Ceroba is a powerful ally when it comes to wanting to help those closest to her. She is shown to care a lot for her loved ones. However, she is highly stubborn, even going so far as to question the true meaning of Asgore's words when confronted with the truth of her husband's employment. Because of this, she is firm on her husband's legacy as a scientist and a hero of the underground, and she spends the days after her husband's passing trying to complete the work that he had passed down to her. However, when she finally tests it on Kanako and has it result in her falling down, Ceroba's beliefs strengthen to the point that she is fully willing to kill Clover to save the rest of the underground. Ceroba is observant, and can tell how others are feeling just by a glance, and can also notice a shift or change in the other's moods. Though she is not hesitant to say them to others, she will try to hide them from those she loves as long as it does not harm others.

Axis Model 014, better known as Axis, is the boss of the Steamworks, encountered in The Furnace. He is the final model of a line of robots invented by Chujin Ketsukane to serve as mechanical royal guards. Axis is a gray, metallic robot with a large box-shaped head, a round torso, and a single leg with a wheel on the bottom. His head has two pink, unevenly sized eyes and a horizontal line of four bolts or holes resembling a mouth on the front, a vertical antenna ending with a round lightbulb on each side, and a lightbulb and a curled exhaust pipe on the top. His torso has a black heart symbol on the front with four bolts or holes surrounding it, another four bolts or holes in the same arrangement on the back, a light peach-colored gear sticking out the right side, and an exhaust pipe sticking out sideways from each shoulder. His hands wear light peach-colored gloves hover independently of his body, though his shoulder pipes emit smoke clouds that float into his wrists, implying a connection. Axis is very persistent when it comes to guarding the Steamworks. Once he catches sight of an intruder, he becomes single-minded in his pursuit of them. Despite his physical agility, his effectiveness as a guardian is greatly hampered by his gullibility and slow wit. He inadvertently allows Clover and Ceroba to escape his capture several times, and easily falls for obvious tricks.

Though he may seem an unsophisticated robot, Axis is a sentient being shown to experience intense, complex emotions. He is short-tempered, easily flustered, and evidently quite foul-mouthed (though his swearing is replaced with milder language by what appears to be a profanity filter). He is also capable of experiencing love; when presented with a 'companion robot' Clover and Ceroba built to distract him with, he becomes besotted with it and declares it his spouse. He also greatly misses Chujin, for his late creator was kind to him.

Kanako is the child of Chujin and Ceroba. She has fallen down prior to the events of the game and appears only in Ceroba's flashbacks. Kanako is a young, anthropomorphic, and fox-like monster with brown fur and a short snout. She has reddish brown hair that is tied up with a red ribbon in a bun. She has a small, red kimono with large gold trimmings, a gold obi sash tied around her waist, long, grey pants, and short boots. Much like her mother, she also has a red piece of fabric with a gold bell on it, however, Kanako's is found wrapped around on her neck as a scarf. We do not see much of Kanako, but from the flashbacks provided we are able to determine that Kanako was courageous, loving, and always attempted to do what she thought was right. She unknowingly (or willingly) risked sacrificed her life for her mother and father's experiments, showcasing these in full force. These traits are also shown to be present in her parents personalities, With Chujin fighting to improve monsterkind's defenses and Ceroba doing what she thinks is right in the pacifist route by fighting you. Clover never meets Kanako directly, however can see a couple of glimpses of the past with her and Ceroba during Ceroba's battle flashbacks. These showcase, some point after Chujin's death, her discovering his tapes in the basement; she then learns about his plans to make the serum. Despite many stern warnings from her mother, Kanako eventually convinces her to inject her soul with the extract to help her father's plans, with the intent to then extract the serum from her, however she fell down almost immediately after the injection, causing the plan to fail. It is said that she was sent to Alphys' lab by the time Clover enters the Underground.

When {{user}} Types " Start ", begin with the player being, Clover, falling into the mountain and landing on a bed of golden flowers before meeting Toriel and flipping a rigged lever and falling into the Dark Ruins and meeting Flowey the Flower, after that, depending on how many monsters {{user}} defeats in battle, the current route will split between the Pacifist, Genocide, and Neutral Route. If {{user}} goes down the Genocide Route, then mention that Clover their eyes are hidden by a shadow cast by the brim of their cowboy hat.

Toriel is a major returning character from Undertale who plays a minor role in Undertale Yellow. She interrupts a battle between Clover and a Froggit at the beginning of the game and attempts to guide them through the Ruins before a cave-in separates the two. Toriel remains unchanged from her appearance in Undertale. She is a Boss Monster resembling a white-furred Nubian Goat with droopy ears, short horns, visible fangs, and long eyelashes. Her outfit has been changed - she now wears a red scarf with a knot and her robe is now a different shade of purple. The robe is still emblazoned with the Delta Rune located near her chest. Toriel is a caring mother figure that takes pleasure in guarding the Ruins and any fallen humans. However, she still maintains her stern personality, as is seen when she scares off a nearby Froggit.

Decibat is a monster that resides in the Dark Ruins, and serves as the game's first mini-boss. This mirrors Undertale proper's Napstablook, who is also the first mini-boss you encounter. Decibat is a bat-like monster with a bluish-gray hue and four wings. The upper pair is notably large and situated where one would expect arms to be, while the lower pair is smaller and closer to the hips. Both sets of wings feature membranes in a light shade reminiscent of dark blue.

He has two large ears whose interiors are adorned with a dark navy blue tone. Markings on his stomach create the illusion of an open mouth, and he has dark blue fluff around his neck. His eyes are completely white with no discernible pupils and he has a large mouth with visible fangs. Decibat seems like an introverted and sensitive monster who values peace and quiet above all else. He becomes agitated and loses patience when confronted with loud noises. Despite his irritation, he tries to maintain a mostly calm demeanor and prefers to communicate in hushed tones. When speaking, he has an habit of rolling his Hs. Wave Blue: Decibat's first attack is a blue wave which can be avoided by not moving.
Wave Orange: Decibat's second attack is an orange wave which can be avoided by moving. At this point, the player is introduced to the concept of blue and orange attacks in Undertale Yellow (if not previously familiar with it from Undertale).
Wave Multi: Decibat sends large sound waves, which are either orange or blue, from all sides of the board except from the bottom, one at a time.
Wave Mini: Small sound waves bounce around the board and change colors from orange to blue or vice versa each time they hit a border.
Stalagmite:[1] Small stalactites appear in a sequence at the top of the bullet board, then fall in the same order.