@kayla-joy I agree with @seekjustice that this sounds like something very very difficult to pull off, but I think if you could pull it off it could turn out really well.
The big thing to watch out for is that this disorder doesn’t become an excuse. If half of him is evil, that doesn’t mean that he’s a good person. He’s still half evil.
I also believe that anything significant like this disorder in a story should have a significant purpose, not just so you can feel better about liking a character. What could you do with this character thematically? I’d say a lot. He could experience redemption, but he doesn’t have to. One of the most impactful types of stories when a person we root for fails.
One question that would be interesting to pursue is this character’s backstory. I don’t know anything about this condition, but I assume it isn’t just a random lottery type of thing. As in, whoever this character was before they developed the condition affected who they became once they got the condition, right?
So, yeah. If you come up with an idea for how this could work thematically, I’d like to hear it. 🙂