Harry never met Ron on the train so was sorted into Slytherin. Without the trio's help he doesn't defeat Voldemort at the end of 1st year and the Dark Lord quickly takes control again. By 5th year Harry and Dumbledore are in hiding and at a last stab at victory they send a Harry back in time to save Tom Riddle before he becomes evil. Well, eviler than he already is.

When Harry was two, he was stolen from his parents and twin brother, the Boy-Who-Lived, and taken in by a muggle circus. But when he was sixteen, he's taken back to the Wizarding World in order to fill out his "destiny". Doesn't mean he'll go easily though! Circus Harry Dark Harry (ish)