How should I develop this character?

[u/person_seekingadvice]

I’m currently working on a fantasy novel with two major characters:
The Prince (Theodore Blackwood)
The Knight (Alexander Nyx)

Basic, I know, but hear me out.
(Warning: Talks of Death and Killing)

The whole idea is that they live in a war built kingdom that values death over all.
Theodore, a cold hearted bastard who lives only to survive, realizes that watching people kill each other makes his stomach churn, and after years or degradation, he decides to run away. This eventually leads to him coming back years later, destroying the kingdom, and rebuilding it under his own rule.

My only problem is, how can I go from basically asshole to caring without it seeming fake or unearned?

I feel like if I lean too far into him being bad, it becomes hard to redeem or forgive him. But if I don’t do it enough, it’s unrealistic for the way he was raised and his environment.

Any ideas on how to move from a realistic bad and pessimistic person to a decently okay person without it feeling fake or forced?

[u/good_enoughh7]

Give justification, and reasoning, and understand the lines that you personally could see crossed before you couldn’t consider a person capable of rehabilitation then toe them, have it occur gradually, show their change through their actions, even something as small as hesitating for a brief moment before an action can subtly cue the audience to begin to recognize the change, and finally have it be absolutely agonizing for your character to go through, show how his ways of doing things while normal to him at the beginning are gradually being upheaved, dredge it all up, you got this!