It only takes a single disharmonious element to throw off the entire composition. Fifty years before Robert Baratheon was to ascend the Iron Throne, Westeros receives one hell of a bad musician. Harry never did care about any player other than himself.

Harry Potter has been banged up for ten years in the hellhole brig of Azkaban for a crime he didn't commit, and his traitorous brother, the not-really-boy-who-lived, has royally messed things up. After meeting Fate and Death, Harry is given a second chance to squash Voldemort, dodge a thousand years in prison, and snatch everything his hated brother holds dear. H/Hr/LL/DG/GW.

A different upbringing leaves Harry Potter with an early knowledge of magic and a view towards the Wizarding World not as an escape from the Dursleys, but as an opportunity to learn more about it. Unfortunately, he quickly finds that there are many elements in this new world that are unwilling to leave the Boy-Who-Lived alone.

The second war with Voldemort never really ended, and there were no winners, certainly not Harry Potter who has lost everything. What will Harry do when a ritual from Voldemort sends him to another world? How will he manage in this new world in which he never existed, especially as he sees familiar events unfolding? Harry/Multi eventually.

At the end of 3rd year, Hermione asks Harry for some help with starting an interesting project. If a dark lord's got a 50-year head start on you, maybe what you need is a little more time to even the playing field. AU, Timetravel, HHr, mild Ron bashing. Minimizing new powers, just making good use of existing ones.