Tender Reigns Our Night (слэш)

When Voldemort collapsed at Harry's feet on that day in May, he left more than ghosts behind: he'd carved scars so deep that even magic itself was struggling to survive. Harry was barely any better himself.
Sent on a Ministry mission to fight for magic's survival, Harry goes back in time with two simple objectives: find and destroy any existing Horcruxes, and stop Tom Riddle ever evolving into Voldemort — using any means necessary. Harry thus finds himself working alongside Riddle at Borgin and Burke's, examining dark artefacts and desperately trying to fulfil his orders.
Although, Harry soon realises it will take everything he’s got to stop himself becoming entangled in Riddle’s twisted yet strangely alluring web of power, ambition, and dark magic.