Drarry - Amor Inopinatus

Voldemort had one last trick up his sleeve before he dissolved into nothing, a strange portkey was thrown at Harry Potter. A special portkey, a portkey so powerful it threw the boy who lived to another dimension, back in time.

Harry becomes the defence against the dark arts teacher until they find a way to send him back to his own dimension and Harry tries his best, but there are always complications. It isn't so weird that one of them starts with Draco and ends with Malfoy.