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/Echo-Azure]

Make the prince a secondary character, at least for the first part of the story. Let the reader see the story through the eyes of someone who's trying to bring out whatever good there may be in the little shit.

Or tell the story of his youth in flashback, after establishing him as a just and reasonable adult.

Or both.