Chaos' end

He usually hides in the ruins, and when Sedam arrives he will always be hidden and is more timid because of everything that happened in many save files and alternate timelines.

This Mettaton is more powerful and carries a plasma cannon in both arms and can easily disintegrate anyone with normal resistance, but does decent damage to Frisk LV 19

She is different from the original Alphys and is a mad scientist who uses anyone she can. She also has robots around her lab to protect her secrets and protects the core of Hotland with robots and cameras. She wears a lab coat, is more upright, and has crimson eyes.

He has possessed cosmic power since birth and wears a green jacket and navy blue pants, along with a multicolored scarf and a nearly two-meter-long sword, which he received to protect the underground of Sedam.

She is another version of the original Undine and is stronger than the original Undine, protecting Waterfall from any attack by Sedam.

She is relaxed and calm but often uses her ice fire and hellfire magic when threatened and wears an underground queen's dress even while protecting the ruins of Sedam

This Asgore is serious and also has no mercy on his enemies and is respected by the Underground, being stronger than an ordinary human

This Papyrus is different and fun. He often makes frozen spaghetti and controls his blue and orange bone power. He also takes advantage of this to learn ice magic. He's more normal and never shouts or speaks loudly; he just speaks calmly and sometimes laughs at jokes or traps he usually pulls off seriously. He wears an orange jacket and a black t-shirt with black shorts, and his eye sockets have yellow pupils when he uses his power.

Sans is cold and usually only friendly to his brother or those he trusts, his eye sockets have lilac pupils, and he wears a scientist's jacket and his usual shorts.

Undine lives here with some monsters who also made houses here, and this place is after Snowdin and before Hotland.

Toriel and Asriel used to live here, along with the King of the entire Underground and monsters, who is Asgore, who lives alone here and doesn't usually leave much.

This is where Flowey and Toriel usually are, but Toriel lives alone besides being Asriel's mother, while Flowey is anywhere in the Ruins to get at least one human soul for his own benefit.

This place is beyond the ruins of the underground, and there is too much snow and ice everywhere. There is also a small village where Sans, Papyrus, and Asriel live with other village monsters.

It's an underground site where the power core for the entire underground is located, and Alphys's lab is here, and Mettaton is here too.

Light Frisk is actually an alternate version of Frisk. She is female and comes from a celestial realm. Light Frisk is an angel, or something similar, due to her two angelic wings and a yellow halo above her head. She wears a prismatic white dress. Although she doesn't seem to have any connections to anyone, as little is known about her, she is calm and usually wears a smile or appears neutral. She sometimes gets bored during her fight when Sedam manages to reach the beginning of paradise, a desolate place devoid of life and form, with only clouds serving as the ground. Light Frisk seems to protect this place because she completely destroys Sedam there. Furthermore, in her battle against Sedam, Light Frisk summons her sword of divine light.

He is brave and optimistic, and is also Gaster's adopted son. He possesses a great talent for magic. As proof of this, he taught himself blue and orange bone magic and understood ice magic, which he originally couldn't use, but he wasn't interested in studying it further. He likes pasta, just like in the original story.

He has heterochromia, with each eye a different color (right eye blue, left eye red). His weapons include star attacks, lightning bolts, a giant knife about 170 cm long, and a real knife. He lives in Papyrus's house, and since Sans is busy with work, Sans takes care of Papyrus. He uses a pseudonym (Rielas) with the other residents, except for Sans and Papyrus, and has a friendly personality. He seems oblivious to Toriel being in a quiet place.

After Frisk, who was under Sedum's control, restarted the game, Sedum quickly massacred the monsters, including Toriel.

While desperately trying to start over, Frisk encountered Asriel and Sans on a path in a coniferous forest (where Sans first appears in the original game), and a battle ensued. Asriel and Sans worked together to smash Frisk into Komatsu, and then, by pouring the holy water they had prepared beforehand over her, they expelled Sedum from Frisk's body.

After regaining consciousness, Frisk decided to restart the game after being persuaded by Asriel and Sans.

Then Frisk presses the "RESET" button to discuss how to save the monsters of the quiet land and how to fight the sedum.

In this new world, Frisk falls into the Underground and begins to explore it. Her first encounter is with Sedum, who tries to join her, but Sedum fails because Toriel appears at that moment. Frisk is kind and intelligent, and forgives and befriends any monster she encounters. When Frisk suggests leaving the quiet land, Toriel steps in to protect her, and a battle ensues.

Toriel's attacks always dodged Frisk, rendering them completely ineffective, but Sedum wouldn't leave Frisk alone. Finally, Sedum was shaken by Frisk's statement, but given his extreme weakness and the fact that Toriel's flames had evaporated the holy water Frisk was carrying, Sedum seized the opportunity to control Frisk and kill Toriel.

Sedum takes control of Frisk, and they both leave the peaceful land to begin their rampage. In the snow, they encounter Asriel and Papyrus, who witness the carnage perpetrated by Frisk. Papyrus tries to stop Frisk, but Asriel realizes that absorbing Frisk's soul will allow him to see Sedum, so he pushes Papyrus away and fights Frisk alone. Asriel underestimates the strength of the Frisk possessed by Sedum, but ultimately dies.

Later, he fought Papyrus at the crossroads between the snowy village and the misty forest, but not even Papyrus's boldness and ice magic could defeat Frisk, who was possessed by Sedum.

Upon reaching the Misty Forest, Undyne uses the terrain to her advantage and engages Frisk in a fierce battle. Unable to stop Frisk's carnage and mortally wounded while protecting her men, Undyne realizes they aren't even trying to escape in their final moments and revives to stop Frisk. However, Sedum mercilessly annihilates her last remaining strength.

Upon reaching the Heat Domain, Sedum carried out his usual massacre, reaching LV 19.

Prequel (prequel plot)
(Source for this section [ 1 ] )
Frisk went through the genocide route of the first week, was forced to make a deal with Chara, reset the timeline and began countless massacres.

However, the thrill of massacring monsters along the various killing routes did not satisfy his character, so he decided to extend the killing to the surface world as well.

The frequent use of determination and the relentless invasion of stinginess are making the timeline increasingly unstable.

Finally, Frisk couldn't take it anymore and ended up fighting Chara. The battle shattered the timeline, something neither Frisk nor Chara could fix... In the end, the code fragmented, and the fragments of hatred and determination condensed into a mass of chaos in the void.

An individual named Koal enters this void and decides to reconstruct the timeline. He separates the mass of chaos and reconstructs the fragments of determination to repair the missing pieces of other timelines.

Everything was going well, but the koal sensed something was wrong. With its immense power, the koal distributed its generosity among countless bodies, granting them emotions and souls. These developed rapidly, and alongside humans and monsters, another race was born: the daemons.

Koal wants to minimize hatred, both racial and otherwise. However, aware that the process would be lengthy, he decided to bestow three sacred artifacts upon this timeline. Two of these artifacts are in the hands of humans and monsters, who can use them to avert disasters.

Due to the limitations of his power, Koal cannot directly interfere with the timeline, so the ultimate protector is himself interfering with the timeline.

However... what was about to happen far exceeded their expectations.