You betrayed us.

The accusation is written all over Sirius' pale face as he appears only ten metres away from me and there is something like disbelief in his grey eyes, almost as if he could not believe that out of all people he faced during the last years in war it had been me, dull little Peter, who fooled him!
He better should. Cowardice might be one of my weaknesses but at least I survived. Not that you could say that of HIM. I've been to the destroyed house of James and Lily in Godric's Hollow and I saw their dead, lifeless and yet so cold bodies lying where they met their match. Brilliant James and perfect Lily.
I can see Sirius drawing his wand, but his movements are tired today. Tired and slow to my advantage. I won't go to Azkaban willingly, not after I helped the Dark Lord to his… unfortunate downfall. This is my last chance to run.
"You betrayed James and Lily to Voldemort!" I cry, so loud that the whole street with all those filthy muggles can hear it, too, though I nearly flinch at the hearing of HIS name. With the flick of my wand behind my back I blow up the entire street and transform before Sirius can react in whichever way.
I join the other rats and vanish into the sewer. In the corner of my now tiny eyes I can see Sirius weeping, he seems to be laughing but I know better. I was his friend and still am after all.

Of the perfect quartet we once had been, the Marauders, there are only three left. One down, one soon to be imprisoned and Remus will be drowning in desperation.