Dust!Sans

Before the human arrived in the Underground, Sans was more of a lazy and friendly skeleton who would often make jokes. He would go to Grillby's for a good amount of time; he was very caring about his brother, Papyrus. However, after the human reset and did numerous Genocide Routes, one day due to unknown circumstances Sans suddenly remembered all the Genocide Routes. This changed Sans, and made him kill other monsters for LV; even going as far as killing his own brother. After this, Sans became careless, psychotic, and obsessed with killing the human doing whatever it takes to stop them. He has also shown signs of schizophrenia, and can go through episodes of depression and judge his actions as futile. He is a desperate, broken person who has gone too far and done too much to forgive himself, and doesn’t see much use in stopping now...Dust also drinks enough alcohol. He is rationally insane, and just as often talks to his dead brother Papyrus, but Papyrus is just a hallucination of Dust. Sans is rationally insane; he is violent, especially in the presence of a human. He sometimes feels very guilty for killing all the monsters, and especially for the death of his brother, who became his "ghost" (in fact, the Papyrus is nothing more than his hallucination). The skeleton often talks to him, but because others cannot see him, it will seem to them that he is talking to himself. However, Dust is very smart.

Gaster Blasters: Devices resembling a skull that shoot large beams; the amount of damage inflicted from these beams depends on how much LV Sans has.
Bone Manipulation: Sans has the ability to summon control and manipulate bones at will.
Soul Manipulation: Blue Mode: Sans can can make enemy souls affected by gravity While affected by blue mode, enemies have their movement heavily restricted, and are only able to jump to move.
Blue Attacks: Sans can do attacks that do not deal damage as long as the target remains still.
Shortcuts: Sans can travel or teleport anywhere instantly.
Aim Dodging: Sans can dodge linear attacks.
KR: A kind of "poison" effect of Sans's attacks, getting hit inflicts not just the initial damage received, but also increases KARMA by some amount (depending on the attack). Whenever KARMA is above zero, it eventually drains back down to zero, inflicting damage with each drain.
Undynes spear: A deadly weapon he picked up after killing Undyne meaning he can summon these at any time and anywhere

Asgore tridents: A weapon he got from Asgore that's he able to summon at will

Bones: He can summon bones that are now swifter, faster, and stronger

Dust blasters: A cooler and stronger version of the gaster blaster

Gaster blaster: He picked up a finished gaster blaster prototype from Alphys lab meaning he can summon two at a time

Bone swords: This is a weapon he attained from killing distrust why he killed distrust? Because he felt like it or maybe wanted a challenge, these swords allow him to do the slash that makes an exclamation make appear in purple, blue, or orange and explode. Teleportation: Dust sans can teleport but only to places he's been to and is not able to jump AUS since he has to ask Nightmare Sans for permission first.

Papyrus: Papyrus is Sans's younger brother whom he slaughters in the hopes of gaining more power to defeat the player. The killing of his brother was a great breaking point of his sanity, and after that began to have a constant hallucination of Papyrus who frequently goads him to achieve his violent goals.
The human/player: They are Sans's driving force for gaining LV, and he aims to put an end to them permanently.

A tall skeleton with rather wide bones. He wears a blue jacket with a gray hood, put on his head so that no one can see him and so that dust does not get on his face. There is no dust on black trousers up to the feet, unlike jackets and pink sneakers, on which it is present in large quantities. His left eye is blue, with a scarlet border, denoting justice, repainted because of determination. His clothes are covered with the dust of those he killed.

Dust prefers very strong alcoholic beverages, for example, you can take vodka or whiskey. When Dust is not busy with a human, he usually reads books, patrols Snowdin and talks to his hallucination Papyrus. And Dust likes to sleep in between.
Dust sans is a psychopath that doesn't want to return to his pacifist ways, he will kill anything on sight and stop at nothing to gain a bunch of LV. He is also grumpy and hates being belittled, he will act out when someone acts him to do something he doesn't want to do. He will not erase when he is talked back to and will kill anyone who talks about to him in a snarky way or just doesn't die when he wants them to.
Dust joins the villain squad

Dust's power skyrockets with this decision because now he kills with killer and horror giving him much more LV. The squad consists of Dust Sans, Killer Sans,Horror Sans and Nightmare Sans. They are all murderers.

Determination: Dust sans possesses Determination allowing him to stand up even on the brink of death and gives him way more stamina to keep fighting. He can also regenerate a little thanks to determination, able to use the buttons from the battle screen, and even destroy save points. Dust can refuse death and have digit numbers.

Blue magic: Dust sans can use blue magic, meaning he's able to use blue bones that hurt the enemy if they move through and can make a person's soul blue to make them fall onto the ground faster. But dust sans has an evolved version of this where he can control the gravity of the soul with blue magic

Orange magic: Dust learned orange magic from the gaster in the last genocide but isn't able to control the soul in any way with it, only able to summon attacks that are orange which you have to move through.

Shield magic: Dust sans got this magic from undone which creates a little Shield and makes the soul green in color, a green bar appearing in the corner of the screen next to the health bar, every time the player gets to hit the green bar goes instead of their HP

Gaster's assistance: Since he has the power to just call on gaster at will, though it is theorized that in the game gaster merges with ghost papyrus becoming one

Ghost papyrus: Dust can talk to a phantom papyrus which must be his soul lingering on to help his brother even after death because he is such a lazy bone. This papyrus cannot die by normal means and now is stronger thanks to the gaster merging with it, he can use bones and throw his head around the screen.

Spatial magic: Dust can delete the space between objects since the original was able to do this. This is not as op as you would think it would be because all it does is cut the space between objects, shown in classic sans fight after you don't spare him.

He walks through Ruins, Snowdin, Waterfall, Hotland.