The Secret-Keeper transference was performed on the afternoon of October the thirty-first, after which Peter was firmly told to return to the house in Pixie Grove as if nothing had changed. That evening, as the sun sank towards the horizon and children began to swarm the streets dressed as zombies and vampires and ghosts, Peter found himself standing in front of his bedroom mirror feeling like he was going to faint.

He was the Potters' Secret-Keeper now—he'd completed the mission that Voldemort had given him over a year ago, and he hadn't even had to do anything except agree to Sirius's proposal. He hadn't wanted to do anything, because completing his mission meant that his friends would soon be finding themselves face-to-face with the Dark Lord.

But now that he was the Secret-Keeper, he knew what he had to do. If he didn't, and Voldemort found out that he was hiding information from him…Peter didn't even want to think about it.

"I'm sorry, James," he murmured as he rolled up his sleeve, exposing his Dark Mark. "Lily, Harry…. I'm so sorry."

He pressed his wand against the Dark Mark until it burned; a moment later, he felt a sudden chill pervade the room that could only mean one thing. "Do you have what I asked for?" Voldemort's voice murmured from a corner.

Peter spun around to face the Dark Lord. "I—I do," he whispered. "Lily and James…they made me their Secret-Keeper. I can tell you where they're hiding now."

"Well done," said Voldemort. "I knew you weren't as incompetent as you pretend to be." A small, cold smile curled his lips. "Give me the address, and you will forever be one of my most valued servants."

Peter closed his eyes; he couldn't look him in the face as he said it. "1703 Augurey Lane, in Godric's Hollow. That's—that's where they are."

When he opened his eyes again, he saw that Voldemort's smile had grown. "Excellent."

"You're only after Harry, right?" Peter said quickly. "Can't you…you know…take care of him and leave James and Lily alone?"

"Severus has asked me to spare the girl's life," Voldemort replied. "I will, so long as she behaves herself. But the baby and his father…they'll both be dead before the night is over."

"Can you spare James, too? For me? Please, I'll do whatever you want, I'll—" But Voldemort Disapparated before he could even finish speaking, too distracted by his desire to kill the Potters to consider Peter's desperate request.

They'll be dead before the night is over. James and Harry, and possibly Lily too…they were going to be killed, and it was all Peter's fault. He turned back to face himself in the mirror, seeing the tears in his eyes that his numb, senseless body could not feel.

"What have you done?" he asked into the mirror, as if it were his reflection who had just betrayed the Potters and not the flesh-and-blood person standing before it. "What have you done?"

But there was no one to answer him, no one but Peter and the terrible, soul-crushing guilt that he knew would haunt him for the rest of his life.