So I remember when you were really into the three siblings and you made a lot of great content with them!! I always thought you saw chara as a damaged kid who made bad choices but through therapy and help from loved ones they were able to change their ways.
This was true and still definitely is! And I still really hope that that's what Deltarune will go for with Kris also!
I just also think Undertale works really hard to tell us that Chara's default personality, back when they were alive, was a messed up little creep who intended to do terrible things - whether they end up going through with those terrible things or if they find peace in death is up to the player's choices.
My interpretation of Undertale has always been that we, the players, play as Chara. We're not controlling them, we are them. That's why they have our name, while only Frisk has their own name.
When we first start the game up, we don't know what's going on because Chara has amnesia. Frisk is the medium we/they use to interact with the world; the 'fight' option is our default option because that's what we expect from an rpg and 'fight' is also Chara's default option because they still have subconscious memories of all the hardships they went through in life, but Frisk, being our vessel, also presents us with the unusual choice to 'act' instead. We/Chara can choose to work together with Frisk on the pacifist route, or force them to fight on the no mercy route. Whichever choice we make is supposed to be the choice Chara makes. And at the end of each route, Chara as a character is separated from the player again and is able to make the last few choices in the game themself, based on how the player decided to shape their character.
If we chose to be kind, Chara becomes kind. If we used violence to make them a god, then they become a god - enough of a god to be able to look beyond the fourth wall and notice we're there at all.
All the fanworks I've made with Chara feature them as a child with problems who's working to get better, because I chose the pacifist route. 'My' version of Chara is a mean little bully who ultimately got a second chance at life and wants to learn how to be better for their siblings. But that doesn't mean they don't canonically have the capacity to become a god of evil, if that's what we, the players, want to be - we don't force them to be evil, we enable them to be.
It also doesn't mean we don't have plenty of canon evidence that before they became a player character, they were mean. Asriel very clearly has emotional scars from their bullying. And I think it says a lot that the route where we actually get to meet them, explicitly, is on the no mercy route. Chara is, in-game, associated with violence and destruction. You have to dig pretty deep into the lore to find evidence that they were also in some ways just a regular little kid who loved their adoptive family and deep down didn't want to be bad.
I understand why Chara fans get defensive over the character, because there is a subsection of the fandom who don't allow them to have any depth and that's annoying, but I also find it incredibly frustrating that so many people grasp at straws in order to excuse or explain away their scarier aspects. Undertale hammers home Chara's tendencies towards bullying and violence extremely clearly, both in-game and in backstory lore, and pretending Frisk, Chara and the player are a whole matryoshka doll of mind control just so Chara comes out of the situation looking innocent is ridiculous.
I love Chara. They're one of my favorite characters in any story ever. But I love them exactly because it's easy to read them as extremely complex and conflicted.
I deffinitely think they can be redeemed. I think they should be, in order for the game's themes to make sense. But in order for a character to be redeemed, they need to have been an actual bad guy first. Same as Flowey/Asriel. Same as Asgore, Alphys, Undyne, Mettaton and all the other monsters who did messed up things but decided to be better. Most of Undertale's cast are reformed villains by the end of the pacifist route. It's the game's entire gimmick.
The whole story is about one child convincing a bunch of adults trying to murder them to calm down and be real cool instead. Chara being a murderous little brat by nature doesn't actually make them all that different from the rest of the cast, and I think it's only natural that they should get to have their flaws and learn from them, just like everyone else.
