A/N: This is a rough version, so please forgive any grammatical errors or funky sentence structure. :-)
Disclaimer: Harry Potter is not mine, otherwise I would be in the midst of writing Deathly Hallows instead of this.
I silently follow Crookshanks across the moonlit grounds of Hogwarts, the knife I stole from the Hog's Head in my mouth. It's hard not just to run full blast up to Gryffindor Tower, but I know that I must be patient. Tonight I can finally get that murdering traitor. The plan seems foolproof this time, Crookshanks tells me that the Fat Lady is no longer guarding Gryffindor Tower (good riddance, I say, I never did like that fat cow. She was entirely too nosy back in the day), apparently Sir Cadogan has replaced her. What possessed Dumbledore to choose Sir Cadogan, out of the thousands of portraits that hang upon Hogwarts' walls, to guard the Gryffindors (let alone anyone or thing at all) is beyond me. But Crookshanks secured the passwords, getting in will now be a piece of cake.
We're climbing up the stone steps; we hide in the shadows, and not a moment later the caretaker comes outside to re-light the torches, their having been doused by the dementors. Crookshanks is the most intelligent animal I've ever met; without him none of my plans would have been possible. We slip inside and make our way through the winding corridors. Merlin, this place brings back memories. How many times did we, the Marauders, traverse these halls, nipping down to the kitchens for a midnight snack, heading to our latest detention, sneaking out to the Whomping Willow for our full moon escapades around Hogsmeade and the grounds with Lupin? The fact that one of us, weak, traitorous Peter, destroyed all of our lives kills me. James and Lily, dead… 'course, I know that's partly my fault as well… how I regret the day I told James to change Secret-Keepers… But tonight I will avenge their deaths and my wrongful imprisonment… I don't care what happens afterwards, just as long as that murdering rat is dead and Harry is safe.
Crookshanks stops suddenly; Minerva McGonagall is intersecting our corridor. Merlin, I miss making her mad, that stern face always made my day, especially when she couldn't control her laughter. I remember our fifth year when we soaped down the entire second floor corridor… ah, memories.
She's out of sight now, all's clear. We continue without further interruption to Gryffindor Tower and stop in front of the one and only Sir Cadogan. Crookshanks delicately pushes the scrap of paper with the passwords on them toward me from behind a potted plant as I transform back into myself. I stretch briefly, pick up the password list and my knife and square my shoulders; I'm ready to capture Peter and give him his due.
"Well, my good sir, have you got the passwords required for admittance to the fine chambers within?" Sir Cadogan is in battle stance, sword at the ready, though he looks like he could be pushed over with a good shove.
"Oddsbodikins, scurvy cur, lionhearted, heather o' the moor." I read off quickly.
Cadogan sighs. "Very well, then."
I suck in my breath as the Gryffindor common room comes into view. At last, I'm in there. Now I just have to find Harry's dormitory.
Crookshanks is one step ahead of me; with a significant look in my direction, he starts trotting up the boys' staircase. I follow him as quickly and quietly as possible, I can't mess up now, not when I'm so close. Crookshanks leads me to the third door on the right, and then, tail in the air, struts jauntily downstairs. That cat's smart, and he knows it.
I tuck the passwords in my pocket and grip my knife tighter: this is it. I open the door slowly, thanking the gods above it doesn't creak. Gotta love those house-elves.
There are five beds in a row, I start with the farthest on the right. I have no idea which bed it is that Ron Weasley slumbers. Knife at the ready, I cautiously part the curtains and peer in: it's Harry. I draw back the curtains further, he's fast asleep. This is the first time I've seen him up close since the day Lily and James were killed. He's nearly the mirror image of a thirteen-year-old James, just thinner, and of course, his scar and Lily's beautiful green eyes, hidden underneath his closed eyelids.
Seeing him there, knowing what he lost and could've had – James and Lily were excellent parents from day one – what I could have had, brings all of my anger and hatred towards Peter – and myself – to the front of my mind. I close Harry's bed hangings and move on to the next bed. It's the Weasley boy! I scan the bed for Wormtail, and just as I notice a rat-sized lump underneath the bedcovers, the Weasley boy rolls over and stares me straight in the face. Frozen and shocked, I stare back until his eyes widen in terror and he lets out a scream loud enough to wake the dead. The other boys wake up at once, and I know that my plan has failed yet again.
I race out of there and down the staircase, taking twos and threes at a time, hightailing it across the common room and out of the portrait hole. I vaguely register Sir Cadogan yelling some nonsense about a jolly steed, but I'm already transforming back into Padfoot. Knife in mouth, I run as if my life depends on it – which actually it does - through the corridors, until I see the one-eyed witch. I transform back into myself, wandlessly open the witch's hump, and off I go to freedom. Or something like it.