AU. Voldemort kills Dumbledore but is defeated by a child. In the aftermath, Snape becomes the Headmaster and radically changes Hogwarts. Harry Potter of House Slytherin begins his Third Year at Hogwarts Battle School and realizes that friend and foe are too similar for his liking. Competing with allies and enemies, Harry finds there is a cost to winning.

A difference of a few seconds can change a life. The difference of a few minutes stained Harry's hands with blood - but for the Dark Lord, it was insufficient. After all, you do not need to kill a man to utterly destroy him. Harry/Tonks

Broken and defeated, the War long since lost, Harry enacts his final desperate gambit: Travel back in time to the day of the Third Task, destroy all of Voldemort's horcruxes and prevent the Dark Lord's resurrection…all within the space of twelve hours.

So maybe everything didn't work out perfectly for Harry. Still, most of his friends survived, he'd gotten married, and was about to become a father. If only he'd have stayed away from the Veil, he wouldn't have had to go back and do everything AGAIN.

The Hero Trilogy, Part One. After the tragedy of his fifth-year, Harry Potter returns to Hogwarts and to a war that will shake the Wizarding and Muggle worlds to their very core. Peace rests on the edge of a sword, and on the courage of Harry alone.