Harry had failed, killed in his sleep by an unknown agent the night before they were going to return to Hogwarts for the last of Riddle's horcruxes. Of course, being Harry Potter meant that he'd been interrupted on his way to the afterlife, told little to nothing beyond the fact that Riddle had pissed off both sides with his soul anchors and that they were going to send him back to ensure Riddle's demise. Harry would keep his current knowledge and his magical core would retain the power it had when he'd died, but he would get no other knowledge or gifts. Not even the removal of the bit of Riddle's soul that sat in his scar.
Worse, he couldn't even choose when he was sent back to, and he'd woken up on his seventh birthday for some kind of unexplained magical reason. Years before he was likely able to so much as contact the magical world safely, let alone do anything. It was almost maddening, most of his mental focus having to go into not killing the Dursleys as they mistreated him. Well, that and remembering just what his routine was supposed to be, since it'd been quite a while from his point of view.
His day changed drastically from the norm, any norm, around noon. There was a mighty crash, as though thousands of panes of glass were breaking, that Vernon didn't seem to be able to hear. Petunia had heard something, but obviously to nowhere near the same degree as Harry had. Ten seconds later three men in fully concealing black cloaks apparated into the room, stunning the Dursleys before anyone could so much as take a breath to attempt to yell at them.
Harry then had to mentally apologize to one of the three, as she pulled back the hood of her cloak. "Good day, Mister Potter. Sorry about the delay, but the absolutely horrid wards on this property held us up."
Blinking, Harry nodded to acknowledge that statement, incredibly confused about what was going on as this hadn't happened on his seventh birthday. "What?"
"My apologies, but we should have at most half an hour before the monitoring devices on the ward alert the one who placed it." She then waved her wand over him, scowled as he lit up like a Christmas tree, then cast a dozen spells faster than he could follow to negate most of the lights. A parchment had appeared listing things as well, though he couldn't see what it said.
"Removing the tracking is probably going to bring someone down on us faster," one of the other two said.
"We're going to need a Fidelius anyway," the woman said. "It'll take at least a week to safely remove the blood trace."
"Damn."
Harry's fight or flight instinct had, during that conversation, finally started to get into gear and he looked for a way out. The three unknowns were between him and the only good exits, and before he got further than noting that a scarf was thrown at him. A moment later he felt the familiar pull of a portkey and mentally swore.
Ten minutes later he was in a very nice looking apartment with the three unknowns, who had thrown up a fidelius with Harry himself as one of two secret keepers. Apparently it wouldn't hold for more than six months cast that way, so one of the men said, but they only needed a week or two.
"Sorry about all of that," the woman said once she had the secret that 'the safehouse is in apartment seven'. "I'm Florence, and your primary contact while we figure things out."
"Figure what out?" Harry asked, doing his best to ignore the spike of pain in his head.
"Why you came back in time outside of a closed loop, of course. There are only six known methods of doing so, four of which we can rule out by you appearing back in an existing body instead of bringing your future body with you. The final two require incredible sacrifices, usually only performed by the truly desperate, and if you did either of those then we're going to have to ensure that you had an actual good reason for doing so. Or, I suppose, that you interrupted someone else doing so and just got caught up in the ritual."
"I have no idea what you're talking about." Though he did find himself thinking about the post-death meeting he'd had, which sounded nothing like anything she was talking about.
There was a pause as Florence rolled her eyes, but one of the men swore under his breath. Florence turned back to him. "What?"
The man pointed at Harry. "He's got no shields to speak of, and he honestly has no clue what you're talking about." He then bowed slightly to Harry. "Sorry for the invasion of your privacy, I'll ensure that the 500 galleon reparation for unauthorized legilimency on an innocent is paid by the end of the week."
"If he has no clue then how the hell did he get here? Sleeping through someone else doing the ritual on him?"
"As far as the kid is concerned, he died and was sent back. Worse is why, we've got soul anchors to find and dispose of."
That had the other man and Florence swearing as well.
It had turned out that the three were Unspeakables of the Department of Mysteries, and one thing the department did was track all time travel. Most methods created a stable time loop as a side effect of the way they functioned, magic itself ensuring that you couldn't change the past. But there were other methods that allowed changing of the past, usually used in an attempt to take over the world before anyone knew you were going to be a threat or to stop someone who was trying to take over the world.
Harry's arrival had been spotted immediately, only for the protections on the Dursley's house to slow the Unspeakables down in getting to him. Florence was pissed at the blood tracker and his general health, they were all pissed that Riddle had created horcruxes, and another Unspeakable that introduced himself as David had been gleeful upon finding out that he finally got to use the ritual that would remove a soul fragment from a living thing without harming said living thing.
That had hurt worse than any Cruciatus curse had, knocked him out for a full week, and for some reason had caused him to be unable to speak or write in anything other than parseltongue. They ended up needing to teach him some of the mind arts just to help him get enough control of his magic to shut down the ability, just happy that he was still able to read and understand English. It was only after that had been accomplished that he was able to properly share the rest of what he knew about the horcruxes.
By Harry's eighth birthday the Unspeakables had acquired everything other than the diary, which was proving to be difficult to get their hands on. They knew what Malfoy had done with it in the original timeline, but couldn't depend on him being that predictable. Nor did they want to risk the diary taking control of anyone before they could track it down. It was Harry, just after finishing his cake, who brought up the possible answer.
"Does anyone think that Malfoy wants Riddle to return to take over leadership again? And if not, would he hand the diary over to prevent it?"
It turned out that the answer was that nobody thought that Malfoy wanted to stop being the de facto leader of the dark and that he was, in fact, willing to give up the diary once informed that it was a soul anchor. Followed by checking his entire family into Saint Mungo's to be treated for exposure to an unknown soul anchor, something that Harry hadn't realized was part of the treatment he'd been getting for malnourishment. Though Harry's was less severe for a number of reasons.
Sadly for Lucius, he was denied his status as the leader of the dark by Riddle's mark. When the diary was unceremoniously thrown through the veil, being the only intentional anchor that hadn't been an important artifact of some kind, the dark mark drained every last one of his followers dry attempting to prevent Riddle's final passing. It didn't kill them, but magically they were all left as less than squibs. Overnight the British magical world changed, far too many purebloods suddenly losing their magic. Others, like Peter Pettigrew, were found in compromising positions. Of course, the discovery of Peter led to the freeing of Sirius, something the Unspeakables had been having trouble arranging, which had led to a very happy Harry.
Dumbledore's actions, both in imprisoning Sirius without a trial and in placing Harry with the Dursleys without proper care and checkups, had led to him being arrested. He was able to get out of being imprisoned, but he lost all of his positions. McGonagall, luckily unaware of the man's crimes before his arrest, ended up becoming the next Hogwarts Headmistress. She named Flitwick as her deputy and fired Trewlany before returning to searching for a replacement potions instructor.
Harry ended up moving in with Sirius, who bought a muggle home as an extra middle finger to his recently-deceased mother. It was only when Harry started attending school again that he found out that the new house was two blocks away from the Grangers. Running into Hermione being bullied for her bookish ways infuriated him. Nobody in the school could explain what had happened, but Hermione and her parents got an early introduction to magic as a result of it.
The future was certainly going to go very differently, and it wasn't until his third year at Hogwarts that Harry realized why no additional 'gifts' were given when he was sent back. They hadn't been needed, after all, as the act of sending him back had ensured that everything was put into motion without needing anything else to help out.