A/N: I know, there are already a ton of 'What if Serious was free and raised Harry' stories. This is my take on it… Begins at the end of PoA.
Butterfly Effect: scenarios involving "what if" cases where one storyline diverges at the moment of a seemingly minor event resulting in two significantly different outcomes.
What if Remus had taken his Wolf's Bane potion that evening…May
Having taken his wolfs bane potion, Remus made his way from Snape's office back to his own, and looked at the Marauder's Map. He was surprised to see all the activity on the grounds, and even more so when he saw an old familiar name. Peter Pettigrew. Shock held him frozen for a few heartbeats. Peter was alive… Everything he'd believed for twelve years was now open to question, and he needed answers. He raced from the room.
A short time later Dumbledore entered the office, hoping to talk to Remus. Seeing the map, he studied it. It was a marvelous piece of magic. He smiled at the names of the creators. Then he saw the situation: Sirius Black – right by Harry Potter. And another name. Peter Pettigrew. He hurried off to the Shrieking Shack.
Dumbledore blinked as he approached the group emerging from the Whomping Willow. From a distance, and unable to see the scar or Lily's eyes, it was all too easy to mistake the dark haired boy for James – especially with Sirius, Remus, and Peter there. But the presence of Ron and Hermione showed it to be Harry and the present – not the past.
"Peter. I never thought to see you again," Dumbledore greeted.
"Professor!" exclaimed Harry and Hermione.
"We have a lot to explain," Lupin said.
"So I see. Please do so…"
Once everything was explained, Dumbledore turned to Lupin. "I'm afraid there isn't time to get you safely back to your office…"
"I'll stay here at the Shack, or in the forest," Lupin replied.
"Sirius, I think it best you stay as well. I'll take Peter and the children back to Hogwarts, and call the Ministry. We'll question him under Veritaserum and clear you, then send away the Dementors. It should be safe for you to return with Remus in the morning."
Sirius nodded, then turned to Remus and gave a real, if sad, smile. "It'll be almost like the old days…"
"Almost," Remus said, with a sad smile of his own. But he couldn't deny it would be good to run with his old friend once more. Especially now he had the wolfs bane potion, and more control.
Harry looked back once to see his favorite professor and new-found godfather watching them. He looked again as they entered Hogwarts, only to see two canine figures disappearing into the woods at a fast run.
Ron was sent to the hospital wing and Madam Pomfrey. The others went to Dumbledore's office, and he began contacting the people he'd need.
Snape seethed as he listened to Peter's story (forced by the Veritaserum he'd happily provided), but he was well enough practiced at controlling his emotions to keep it from his face. The Rat had betrayed Lily! All these years he'd hated Sirius, and it had been little Peter who'd caused Lily's death. He knew exactly which Death Eaters to tell this too, and exactly how to play the story. This time his cover as still being a Death Eater would be very useful. Peter would pay for his betrayal of Lily.
Once the story was complete, Dumbledore turned to the Minister. "So, given this new evidence, Sirius Black…"
"…is cleared of all charges. The Dementors will escort Mr. Pettigrew to Azkaban," Fudge said.
"And remain there. They are no longer needed here," Dumbledore stated.
The Minister nodded.
"I'll see these two back to the Common Room," McGonagall stated, looking at Harry and Hermione.
"Thank you, Minerva," Dumbledore replied.
Harry was exhausted, but very happy, as he climbed into his bed. He had a godfather, and his parents true betrayer had been caught. He wouldn't have to go back to the Dursleys.
Not long after sunrise the two exhausted friends entered Hogwarts. Remus turned to the large staircase, but Sirius saw Snape heading down into the dungeon area and stopped. "I'll be up in a few minutes," he said, then followed Snape.
Hearing someone behind him, Snape turned. "Shouldn't you be in Dumbledore's office?"
"Yes. But I need a few words with you first, Snape."
Snape led the way to his office. "Make this fast, Black."
"You've hated Remus because you thought he was in on the… prank I pulled on you 6th year. He had no idea, Severus. He was furious with me when he found out. So was James. And let's not even start on the telling off I got from Lily - I'm amazed you didn't hear it even down in the Slytherin dungeon."
"Really," Snape sneered. "You seemed close as ever after that incident."
"We weren't going to show weakness or division in front of a bunch of Snakes – especially with Bellatrix, Regulus, and other Black family connections watching. Only the Gryffindors knew how bad things were with our group. I honestly never imagined you'd think Remus was in on it. No one who knows him would believe that… But I didn't consider how little you knew him. That prank was mine alone. If you want to blame someone, blame me. Don't take your anger at me out on Remus… Or your hatred of James out on Harry." He paused for a moment. "And if you're truly the person Lily thought you were, you might consider accepting my twelve years in Azkaban as suitable punishment for what I did. I know you two never talked after that day, but Lily did miss you – terribly. Losing your friendship was one of her few regrets in life."
Snape considered for a moment. "I suppose an actual apology is too much to expect."
"It wouldn't be genuine," Sirius admitted. "I don't regret what I did. You were trying to get us expelled. Remus' life was hard enough without his secret being exposed to the world. He didn't deserve what would have happened if you'd exposed him… And, Severus, make no mistake: I will still do anything I must to defend those I care about – most especially my godson."
They looked each other in the eye for a moment, then Sirius left. They still didn't like each other, but they did understand each other a bit better. For a long moment Snape considered telling his students that Remus was a werewolf, but decided against it. Dumbledore would be more likely to give the vacant teaching position to Sirius than him. And he'd seen the truth in Sirius eyes when he'd said Remus hadn't known about what Sirius was planning. Snape decided he needed to focus on Peter, not Lupin.
A short time later Sirius was in the Headmaster's office. "I'm going to find a place as soon as I can. With any luck, Harry can join me as soon as the school year is over," Sirius said. He was so happy that his godson wanted to live with him that he couldn't keep a wide smile from his face.
"I'm not sure that is possible," Dumbledore said. "Lily gave her life to protect Harry. It worked a very old and powerful magic, and gave Harry protection as long as he calls the home of a blood relative his home. I know James was like a brother to you, Sirius, but you aren't Harry's blood relation. Living with you, he would lose that protection. He needs to live at the Dursley's at least a few weeks a year until he turns 17."
"Perhaps not," Remus said. "You know Lily's parents were killed by Death Eaters when they were trying to find Lily, James, and Harry." They'd been killed in London; since the Wards Lily, and the others, had placed on the home had made it impossible for the Death Eaters to find the home.
Dumbledore nodded, as did Sirius.
"By then Petunia and Lily were both married, and had their own homes. Harry's grandparent's home was left in trust to Lily, for Harry. I believe it's still in the grandparent's name, officially. Under Muggle law it's still their home, even though they're dead…"
Sirius grinned. "You're brilliant as ever, Remus."
"It should work," Dumbledore agreed. "But let's not tell Harry about this just yet." He held up a hand to silence the protests he knew were coming. "The parents of some of our students are Death Eaters, or at least sympathetic to them. If Harry does anything unusual it will be reported to the parents… We tell Harry that after twelve years in Azkaban you need a little time to arrange a home for him. That he must return to the Dursley's for a short time, but that you will get him as soon as you have a home ready. Then, you can be waiting there for him on Privet Drive, to tell him the truth and bring him to his new home. I'll send Dobby and some of our other house elves to make sure the house is ready to be lived in after twelve years of being vacant."
Sirius reluctantly agreed. While Harry had agreed to come live with him, Harry would certainly want to at least say farewell to the Dursleys and get his things.