the_debt_of_time

Remus and Sirius reacted instantly, and Peter was thrown back on the ground,
coughing as the breath was knocked from his lungs. When he finally was able to gasp, he
looked up at them, horrified. Remus could only imagine how he looked right then. Years
of experience had taught him to feel when the wolf was at the surface, and he could almost
see his own golden gaze reflected in Peter's wide-eyed stare. Sirius was breathing hard
beside him, snarling viciously.
"Sirius, what could I have done?" Peter cried. "The Dark Lord... You have no
idea. He has weapons you can't imagine. I was scared, Sirius. I was never brave like you
and Remus and James. I never meant it to happen. He-Who-Must-Not-Be-Named forced
me―"
"Don't lie! You'd been passing information to him for a year before Lily and James
died! You were his spy! It was you who betrayed us and set up that trap. You killed Mary,
didn't you?" Sirius snapped and tore at the sleeves of Peter's robes, revealing the Dark Mark
on his left forearm.
Peter wept.
"You should have realised," Remus said quietly, "if Voldemort didn't kill you, we
would." Twelve years. For twelve years, he had mourned Peter right along with James and
Lily. For twelve years, he had broken his promise to Mia and had chosen to not trust Sirius.
Remus had never taken a life, not even in battle. But this... this would be worth it.
"Goodbye, Peter," he said callously, raising his wand at the same time as Sirius.
"No!" Harry yelled, running forward. He placed himself in front of Peter, facing the
wands that were immediately withdrawn. "You can't kill him."
"Harry," Sirius said, panting with anger. "This... rat is the reason you have no
parents. He stole their lives, stole my life and everything from me."
"I know. You still can't kill him."
Sirius and Remus both shook with rage.
"We'll take him up to the castle," Harry said, looking at both of the men with
pleading eyes. "We'll hand him over to the dementors. He can go to Azkaban."