A/N: Just a very short scene I wrote a few years ago after getting into the Harry Potter series again. I imagined the scene in which Sirius confronts Pettigrew and felt compelled to write it down. There's violence, so I guess I'll rate it M to be safe...
All characters etc. property of JK Rowling.
He had no idea where he was going—just running flat out, heart in throat and breaths sharp, fighting to keep Pettigrew in sight. Trails of blood snaking across his left fingers where he had split the bastard's lip, before raising his fist again to pummel Pettigrew's head into the wall until his skull split but too late—Pettigrew had transformed and ran. Not quick enough, however, to escape Sirius' sharp eyes, to escape the stinging pain of a hex that caused him to lose focus and shift back into a man. Only sheer terror could make Pettigrew regain his footing so quickly, and he ran. Sirius was closing the gap now, eyes hard and focused upon the fleeing coward while his mind swam.
He was there, he was in reach—Pettigrew twisting and crying out as Sirius grabbed him by the coat, wrenching him around.
"YOU GET BACK HERE RIGHT NOW! YOU FACE WHAT YOU'VE DONE!"
Sirius gripping the collar of Pettigrew's shirt, hauling it to the level of his throat, twisting, wand tip pushed between Pettigrew's eyes. Lips curled into a snarl and rage within his gray eyes.
"Lily and James, Sirius! How could you?"
The roar and light threw Sirius backwards, glass shattering and raining upon him as the adjacent shop window was blown to pieces; adrenaline drove him to his feet and when he had turned again his legs gave, glass crunching under his knees. Bodies littered the walkway, skulls of the nearest blown apart, blood pooling and beginning to run in streams. The wailing and screaming distant in Sirius' ears as he felt with a finger the blood spattered across his face. Raising his eyes he noticed one severed finger a foot away from him, exactly where he had caught Pettigrew, and the laugh burst from his throat. Hysterical, uncontrollable laughter that wracked his body and he ground his elbows in the glass, lowering his head to the walkway as he simply laughed in the face of it all.