Something I recently learned about writing is that a character should never stop feeling flawed. It doesn’t matter how much (positive) development they go through, a realistic character doesn’t completely erase their flaws at the end of their story, and that’s okay! You’re never going to reach perfection, so there’s no reason for a character to stop feeling a little broken, a little evil, a little off, that doesn’t invalidate their growth, it only makes it more real.