Error! Sans

Error! Sans is an AU destroyer. He is bent on destroying all AUs and things he considers 'glitches' or 'mistakes' in the multiverse. He uses blue strings to tie up and shatter souls, and if the strings go inside a victim, he will be able to transfer his soul into the victim, controlling them to do whatever he likes and leaving the victim helpless. He can jump from one universe to another, as well as having several other glitch powers/quirks.

Error! Sans was created as a result of a player messing with the game files too much, resulting in him glitching out. He found himself trapped in the white void between game files. He went insane in there until he found out how to manipulate the game's code to open portals to various AUs.

Error basically is an AU hunter, seeking and destroying AU's left and right, except for the ones he likes such as OuterTale and UnderNovela, or the ones with powerful guardians, such as the NEO Prime Zone. How he does it is he keeps its protagonists under guard so they are unable to reset (he basically imprisons them), then proceeds to go on a killing spree.

Error was a glitched skeleton that was created in the Anti-Void. He is the result of an alternate Genocide Sans playing with his DETERMINATION and sending himself to the Anti-Void, where he turned into Error.

Biography
Error! Sans found the NEO Prime Zone and tried to erase it. However, Bowser Jr. transformed into Enerjak, who was too powerful for Error to handle. Error then reveals that he watched another AU that he couldn't reach, since it was inhabited by both Classic Sans, Underswap! Sans and Underfell! Sans. He then reveals the story of the Funtime Animatronics, as of how Funtime Stuart was cursed and killed, and how a distortion in the time-space continuum occurred right afterwards. He then tells Bowser Jr. to be on guard, before he vanishes.