Two lonely and insecure persons become friends. Dark!Harry and Auror!Tonks
Harry takes his revenge on "Wizarding World" in a way that is bloody and below-belt blow. He doesn't forgive, he doesn't forget and he kills them all. Harry Potter: lone remaining human alive on ruined desolate wasteland battlefield with countless corpse. Dark! Evil! Cruel! Sadistic! Harry.
Racial! Harry destroys entire goblin nation single handedly. Harry hates Goblins! He kills, NO! butchers them like sheep. Dark! Evil! & Sadistic! Harry.