Drarry
You know the fanfic Harry Potter and Welcome to Grey's World? Well, it's similar in terms of the mentor dynamic with Voldemort, but the relationship with Draco is different.
Draco asks that anything related to his parents be done with him, and Harry doesn't like that very much. Their relationship evolves throughout the story.
There's also Harry's conflict with the Order of the Phoenix, because he wants to end the war but doesn't want to hurt anyone, even while he's with Voldemort.