Two hours later, Peter had finally finished magically cauterizing and bandaging his severed finger. With the pain significantly dulled, he turned his attention to next steps. He was currently slumped against a shelf in the back aisle of a deserted store, warded well enough to divert Muggles and alert him to the presence of wizards. It was a safe place to think, but not a safe place to stay long-term.
Who could he trust? He had thought that surely Sirius would help him; Sirius was the one who had always been there to take a curse for him and then give back as good as he got. He was also the only one alive who already knew what they'd done with the Fidelius. Peter could feel his heart pumping faster with anger and rejection and the pain of his disfigured hand. He took ten deep breaths, reminding himself that Sirius had had an emotionally fraught childhood and always reacted badly to loss. It wasn't quite enough to forgive his friend immediately, but he knew they would be able to reconcile things someday, once Sirius had grieved and then calmed down enough to listen.
Remus might or might not be more willing to hear him out. It didn't really matter; he was undercover with a werewolf clan, and any contact from the outside world risked exposing him. Even if he came back to London, he didn't have the resources to hide them both from Death Eaters; there was no Lupin family mansion to protect them with ancient wards.
His own family was out of the question. His mother had died of the same dragonpox epidemic that killed James' parents. His father was a muggle, and at Peter's urging, he had moved out of the country for the duration of the war and never told Peter where. Even if Peter could figure out how to contact him, it would only increase the chances that the Death Eaters would find him and try to forcibly extract Peter's whereabouts.
Dumbledore probably had the means to help him, but he was a busy man. Peter had gone to him in second year when certain Slytherins had been especially cruel with their bullying. Dumbledore had heard him out briefly and promised to meet with the bullies when he next had an open spot in his schedule. As far as Peter knew, the meeting might never have happened; the hexes and taunts certainly didn't stop, and Peter had learned to stay close to his friends when wandering the halls. Dumbledore probably had even more important items on his agenda now: various Death Eaters were being tried in the Wizengamot, and the Chief Warlock needed to ensure that justice was done. If Peter went to him, he'd most likely be offered a "safe house" with a few minutes' hasty warding, or else referred to a ministry office that would do the same.
That left the other Order members. The Weasleys were always kind, and Molly had offered Peter dinner more times than he could count. He always felt bad accepting charity from such a poor family, especially after they gave birth to a seventh hungry mouth, but perhaps he could make himself useful enough to justify staying with them. The Tonks were another option, but Andromeda was too close with Sirius. He would likely lean on her for support until he was ready to reconcile with Peter. The Longbottoms had the best-warded home of the bunch in their family manor. They'd been very close with both the Potters, and Peter flinched at the idea of trying to explain things to them, but they were both smart and reasonable people. Mrs. Figg was another one who had always been kind to Peter, likely because they were the two weakest members of the Order. She would have no ability to defend him, though, and her family had cast her out once they'd realized she was a Squib, so it was yet another impractical option.
Peter continued to search through Order members who might be able to help him, and when he finished, the Longbottoms seemed like the best option by far. As a bonus, staying with them would allow Peter to help keep an eye on the second possible child of the prophecy. It certainly seemed more likely at this point that Harry was the one destined to beat Voldemort (and possibly even had done so already), but with the Wizarding World's attention focused on him, there was more potential good to be done by supporting Neville just in case he was the true chosen one.
I could train him, Peter thought. I have plenty of experience being the weaker one in a fight, and anyone who fights Voldemort will need to learn enough tricks to take down a stronger opponent. I could spy for him, help keep him safe… Peter cut himself off. There would be plenty of time to brainstorm with Alice and Frank, if they accepted him. At this point he wasn't sure whether he would actually be helpful or whether he was just desperate to find a reason why his life was still valuable after he'd betrayed his best friends.
Peter let himself cry for a few minutes, hunched over on the cold tile floors of the darkened store, then dried his eyes and apparated to Longbottom Manor.
Peter knocked on the door, wincing as only three knuckles connected where there used to be four. That'll take some getting used to. There was no answer for a few moments. That didn't mean much; the Longbottoms were smart enough to take their time preparing a potential escape route and scrying to identify their visitors before answering the door.
Eventually, Frank poked his head out, a shield glimmering around it. "Peter? What are you doing here?"
Peter tossed him his wand (the backup one he'd been using, since the Death Eaters still had his real one) and held his hands up above his head. Frank cast a quick verification charm to make sure the wand really belonged to Peter, then cast a series of charms to make sure that Peter wasn't polyjuiced, or confunded, or carrying certain dark artifacts, or in possession of another wand, or being impersonated by a metamorphmagus. Once he was done, he pocketed Peter's wand and kept his own wand trained on Peter, in case he was imperiused (or there to harm them of his own volition).
(Peter had always really admired Frank and Alice. They thought things through, they didn't take pointless risks, and they'd only become more paranoid when they went through Auror training. They were as willing to sacrifice themselves for the cause as any Order member, but if there were ever a safer way to achieve the same goals, they were smart enough to find it. Even the order of the detection charms Frank had cast was carefully selected to minimize risk, prioritizing types of deception that were more dangerous first, weighted by their relative probabilities.)
((Peter realized he was still standing on the porch, thinking instead of answering the question.))
"I need help. The Death Eaters are after me. Sirius is after me too… I don't know if he's contacted you, but if so, please give me a chance to explain."
"Are the Death Eaters following you here?" Frank asked.
"No, I lost them a while ago. They'll probably check all the likely places I might be, though. Not sure if they'll think to look here." Peter answered honestly.
"Come on in, then. Alice went to send Neville off through the Floo when we heard knocking. Can I get you something to drink?"
"If you want to feed me veritaserum, you can just ask," Peter rolled his eyes. "My story's true, and we'll both be happier if you can trust me completely."
Frank laughed. "I'm glad you understand. It seemed a touch impolite. One drop, then?"
Peter nodded. Frank kept his wand trained on him until Alice returned, and then she took over while he went to prepare tea. Peter assumed Frank would mix in a tracer agent too: something magic could easily detect in the bloodstream, so they would know he had actually consumed the veritaserum instead of vanishing the liquid as it touched his lips.
While he gulped the cup down, Peter thought about where to begin. "It all started when Sirius suggested we make me the Secret Keeper…"
