Books with a complicated dynamic between the big evil sorcerer/hero?

I recently finished the video game Sea of Stars. Really enjoyed it, great game mechanically, tho sadly felt the overall plot was just ok aside from one interesting element: the dynamic between the godlike evil alchemist and the equally godlike benevolent one.

Specifically, I liked how these two characters still clearly deeply cared for one another, despite trying to defeat the others’ plans over many years and multiple timelines. I also liked the implication that they could likely have killed one another by now, especially since in Reshan’s case, doing so would have ended the suffering of countless worlds/mortal lives, but he can’t bring himself to.

Basically, felt like big divorce energy and they’re making it the whole universe’s problem, including the game’s protagonists, who are kinda also just pawns, even if one of them purportedly cares a bit more about their suffering.

Might be too specific, but does anyone know any books with a similar dynamic, where the big bad evil sorcerer/alchemist/whatever has a similar kind of complicated relationship with the protagonists or a benefactor?