What if Harry Potter's power was just getting his godfather Sirius Black, a trial which would lead to a vanquished Voldemort once and for all? One Shot, literally just a synopsis of what could be a fairly long fic because I'd rather fovus on my current WIP but I had to get this out before I forgot about it in my head, literally no planning or refinement, whatever.

Harry Potter was blasted back into time after his battle concluded with Voldemort with a massive bang and a bright rainbow light. "What happened? Where's Voldemort? Is this..." Harry bent down to pick up a recently discarded copy of the Daily Prophet and read the date. Harry nearly passed out when he saw that Sirius had just been imprisoned. 'That means that I somehow got sent back to 1981!' Harry shouted in his mind.

Harry knew what he had to do. He went to the Burrow where a tired but joyful and slightly smaller Weasley family resided. He waited and watched until he noticed a dirty fat rat scampering about. It decided to take one of the chicken eggs laid in the coop which Harry thought was rather odd and knew this must be Peter.

Harry conjured a cage and placed an unbreakable spell on it, summoned the rat into it and locked it. The rat squeaked loudly and tried escaping but it was futile. He apparated away to get some spare parchment, ink, and quill and wrote down several notes. One was about the cage with the traitor Pettigrew, the next was about Barty Crouch and his plan to break his son out of Azkaban. Third was a note he'd send to Sirius after he was free.

He dropped the cage off at the DMLE with the note on Amelia Bones' desk. He waited impatiently for several days watching and waiting, until finally it was discovered and when Sirius finally got freed at the trial based on the fact that Pettigrew was still alive and the information on the note. Sirius was freed and Harry sent the note he'd written.

Sirius read the note which told of several objects to hunt down once he'd recovered. Armed with the anger at his best friends' deaths and the loneliness that came with it, Sirius hunted down Voldemort's horcruxes with a vengeance which proved almost no obstacle. He apparated to the Shrieking Shack, went up the passage and headed into Hogwarts where he found Ravenclaw's diadem.

He then busted into his mother's home and despite her screams and curses, a quick search later and he found the locket.

Then while the trials for the other death eaters were happening, Sirius broke passed the worn down wards at Malfoy manor and retrieved the diary.

With his family's knowledge of the dark arts, he destroyed the protections surrounding the ring and the resurrection stone though he did feel pressured to put it on beforehand. He had only succeeded as his anger was still boiling at Pettigrew and Voldemort.

The time it had taken for Sirius to do this was about two weeks when suddenly he heard about Gringotts being broken into by a burnt and smoking masked and cloaked figure but they'd yet to discern what had been stolen due to the protections in the Lestrange vault. The cup later then mysteriously found its way to Sirius' side along with the instructions to meet the future Harry at the infamous Moaning Myrtle's bathroom on the 2nd floor.

As Sirius made his way back to Hogwarts, Harry had went down to the chamber with a massive crate full of waking roosters which killed the basilisk once he'd called it out. Being careful, he snapped off a fang and waited for Sirius.

Just a few short moments later, Sirius arrived and they killed all of Voldemort's remaining horcruxes and Harry bid Sirius adieu, arming him with the knowledge that Voldemort was now truly dead, though he did mention where his previous-self lived. Sirius once more enraged to the utmost, stormed off to Dumbledore's office.

The future Harry then made his way to Privet Drive. He wondered if the ward was still running and sure enough, when he arrived, he felt its energy, though it was weak. Future Harry snorted knowingly and went to find past-Harry who was of course stuck in a room without any care in future-Harry's former house. Not sure if it would work but determined anyways, future-Harry cast the killing curse and not two seconds later, the final horcrux piece shrieked and died. The wraith-like form of the fallen Voldemort also felt the pull and he finally passed on where he was sent to Hell. This also caused every single marked death eater to burn into ashes as the magic that connected him to his followers and vice versa pulled them along with him in his passing. With this final act, the magic keeping the future-Harry alive and in the past, faded out of sight and existence while his magical power fused with his past-self.

Past-Harry woke up after passing out, feeling great though he wasn't sure why, though the young baby giggled at the warm feeling spreading through him. Just an hour later after future-Harry departed, past-Harry was picked up and soothed by Sirius who'd began to cry after Sirius won a screaming match against both Vernon and Petunia Dursley.

Sirius never knew that future-Harry was who he was and never found out. The past Harry though raised by his godfather, was tamed by Remus Lupin so he grew proud and strong but not arrogant and rude.

Though life wasn't perfect in the British magical world for many of its citizens, those who fought against the dark side had lost too much to stop with the death of Voldemort and his death eaters and politically fought his unmarked supporters and eventually the ideals that gave way to the rise of Voldemort and his military campaign were crushed under the heel of a reformed ministry.