PETER

As he scurried along the streets of Westminster, Peter Pettigrew turned up the collar of his coat, yet still he shivered. This state of jittery panic had gripped him ever since he had divulged James's location to his new master; when the news came that the Dark Lord had fallen, Peter had run.

Nothing could have prepared him for this. He had been expecting safety, inclusion, rewards even … but nothing had gone to plan. That safety had been destroyed when the Dark Lord had been destroyed, and now he was vulnerable once more.

Of course, other than his fellow Death Eaters, only one person knew of his betrayal. But if Sirius were to tell the Order the truth, the might of the Ministry would be after him this very moment. Muggle London was the perfect place to hide: not just for its population but because it inhabited the largest network of rats in Britain. The merest squeak of danger would be enough to alert him and ensure his survival.

Peter slowed to a brisk walk and marched alongside the spiky black railing that enclosed the back of St James's Palace, checking over his shoulder every few seconds. He was naturally paranoid. He was a coward, and he knew it. Sirius and James had been kind enough to remind him of it for the last decade. The lines between friends and bullies had faded where they were concerned; if they had known the impact all those petty insults had really had on Peter, they surely would have thought twice about it. Too late now, thought Peter savagely. Look where James ended up …

'PETER!'

Lost in these poisonous thoughts, Peter jumped out of his skin. He knew that voice. It belonged to someone he once admired, though someone he now feared. It was the voice of an old friend and a new enemy.

Spinning round, Peter saw him almost immediately. The alley was fairly busy still; late-night shoppers were filing along, a scruffy black man was singing with a battered guitar, and a Royal guard stood poised by the back gate of the Palace. Then shoving his way through the crowd was Sirius, straggly-haired with murder in his eyes.

With his heart ramming against his ribs, Peter slipped his wand behind his back, and advanced. Coward, was he? He'd show Sirius …

'Lily and James, Sirius!' he wailed, so that the whole street looked their way. Peter was simulating sobs of grief now, and Sirius backed against the Palace railings in disgust. The guard remained motionless, though his eyes flickered their way. 'How c-could you? They were your f-friends …'

'Why, you lying, filthy piece of –' hissed Sirius, drawing his own wand in full sight of the Muggles. Many of them screamed, evidently thinking he had pulled a gun, and the Palace guard finally moved to step in –

BOOM

The force of the explosion threw Sirius to the ground, and rubble rained upon him. His ears were ringing as he slowly raised his head, and the screams of Muggles echoed distantly. He half-opened his eyes, blinking against the cloud of dust. His breath caught at the sight of the dead Queen's guard, whose features had been mutilated; blood as red as his coat covered the man's face, his black wig pointing askew.

Sirius staggered to his feet. His mind was slow, his thoughts jagged.

Where was Peter? He can't have gone far, and once he caught him, he could turn him in …

It was then he looked into the web-like crater in the middle of the road. The explosion had punctured the hissing sewer below, leaving a hole large enough for a rat to escape through. All that remained was a pile of bloody robes and a single, fat finger.

Sirius's head swam as he pieced together what Peter had done. He had sold James and Lily to Voldemort. He had framed Sirius for his betrayal. He had caused the death of numerous Muggles and faked his own in the process. He had escaped.

Sirius felt aside from himself, detached, as though he was experiencing this internal devastation from a distance. Peter had done all that. Sniffling, stupid, cowardly Peter had pulled off the perfect crime.

As he did his best to process this impossibility, the echoing noises of chaos sharpened, and his hearing clarified. It was only then Sirius noticed the noise escaping his own mouth.

He was laughing.

What happened next passed in a blur. Wizards appearing on all sides. Ropes binding his hands behind his back. His wand being snapped in two before his eyes. And all the while, Sirius laughed.

'… Sirius Black, by permission of Bartemius Crouch, Head of the Department of Magical Law Enforcement, you are hereby arrested for the murder of Peter Pettigrew and twelve innocent Muggles …'

How could he have made such a catastrophic error? Why on earth did he think he could trust Peter?

'… also charged with being an accomplice in the murders of James and Lily Potter, and the attempted murder of their son Harry …'

If only he had made himself Secret Keeper … none of this would have happened …

' … For these unspeakable crimes, you will be detained in Azkaban, without trial, where you will serve a life sentence …'

James and Lily … Prongs ... dead …

'My fault,' he said, still chuckling, as he and the Ministry officials Apparated onto the cold blustery rocks outside Azkaban prison, where a thousand Dementors roamed the skies. 'All my fault.'

'That's the spirit. No one likes a liar,' jeered the Junior Minister of the Department of Magical Catastrophes from beneath a lime-green bowler hat. 'Find the safest cell you can, boys.'

Sirius chuckled weakly all the way to the highest cell in the very centre of the prison. The Dementors swooped, excited by the arrival of a new inmate. Sirius would not give them what they want. He would remember his innocence and use it as a Patronus. And in the depths of his broken mind, one thought found its mark and it filled him with a boiling hatred.

Kill Pettigrew.

Sirius began to cry.