During Harry's fourth year, everyone betrays him. So when he's reborn back in the Marauder's era, he's going to set things straight. Harry/Narcissa/someone else.
Harry grew up deprived as a child, and the day before his Hogwarts letter comes, he figures out that he has a power over his relatives. Watch as a smarter and less trusting Harry takes over the world. Slytherin Harry! Neville BWL! (on hiatus)