Time to tell more about one of most important characters in Prime!Error's history, Error!Chara down below:
Basic information about her:
Alias:Chara, 501, Rose, Error's little helper
Code:Composed of various Shiftfell AUs that were glitched by the Anti Void.
SOUL:Composed of various glitched Chara SOULs.
Chara's existence was a spur-of-the-moment decision from Prime!Error, born from the latter's jealousy of Ink and his companions. Error had wondered, constantly, "What makes them brats crowd around that freak? Don't they know he's SOULless? That he doesn't care about anything or anyone as long as it helps the AU's scripts? He's faker than a damn Flowey! At least I never lie to anyone. Hell, I even have a SOUL!!"
And this feeling had only increased with each battle until one day, one of Ink's words had landed a bit too close to home in the middle of their battle. "What? Gonna go back and hole in your Anti Void again? Geez, how do you even like that place anyway? So empty and colorless; who'd even wanna live there!? Other than you, anyway. Then again, nobody would want to live with you as well."
And this had fully convinced Error of the plan he had been thinking off for the past few weeks. Initially, he had intended to kidnap a Chara and throw them into the Anti-Void for a few weeks before deciding against it after remembering Swap!Sans.
So, he decided on a longer but more 'humane' path. Immediately upon coming back into the Anti-Void, he had quickly gotten into work, lowering various Chara SOULs he had in the Anti Void. His initial plan was to create something similar to Classic Chara before deciding against it as hanging around a kid as a companion, in Error's voice, would be kind of pathetic.
So, he chose to steal the code of various Shiftfell AUs, using them and their Charas as a model to form Error!Chara, also known as 501, here.
Error!Chara's personality is what you would expect from an amalgamation of various Shift!Charas. She's sassy, quippy and weirdly cheerful despite the very morbid things she does. One of the core things about her is her curiosity, a holdover of her DETERMINATION, she is very curious about the Adamsphere and tries to learn as much about it as possible for learning sake, unlike Error only learned it to destroy AUs better.
Another is her status as Error's companion. Normally it only involves her staying by his status both when he is destroying AUs or in the Anti Void, simply watching and talking with him as he does things.
However, one turning point came after the death of King Zagreus, one of the few people Error could say was his friend. This caused Error to have a massive crash out in the Anti Void and eventually hole himself in there for decades and later on centuries, rarely going out in the Adamsphere until the events of Xtale brought him back to an active status.
While Error appreciated her company at the beginning, he soon became more annoyed at her as she kept by his side at all times, even though that was what he told her was her purpose. Eventually one day, caused by himself crashing after accidentally remembering Blue and a result of him isolating himself in the Anti Void, he crashed out at her and told her to forget his previous command and just leave him in the Anti void for good so he can finally have "some fucking peace".
Error!Chara was of course hurt by this because she actually saw Error as someone close to her. This caused her to leave(though she still checks up on him from time to time) the Anti void and began her own journey, eventually establishing a small group of Charas who don't identify themselves with the Lokanai Kingdom or Nightmare.
In the current age, she and Error have made up completely and she often tells him of stuff happening in the Adamsphere, keeping him up to date.
Unlike before, their relationship now is truly of companions.
Art of her by @miaozers-s