He was a rat.
He'd been pushing back the lack of dignity ever since the inner working of his soul had been exposed so brutally: Peter Pettigrew was a rat, not a proud a noble stag, not a loyal and playful dog. They'd all been transfixed when James had first transformed in their dormitory. Peter remembered that even Sirius hadn't been able to find anything to fault with a stag. Sirius had been satisfied with a dog too – Peter always assumed he liked the dramatic jet black of his coat, and the idea that he was something so agreeable as a dog had done little to deflate his arrogance. There had been some teasing on that front: James had delighted in instructing Sirius to sit in public places, or by patting him on the head and saying 'good boy.' It had been nothing to the extent of teasing that Peter had received.
A rat. So lacking in glamour, sophistication and pride. Another dent in a caving ego.
It seemed fitting to Peter that he would be a repulsive creature in both human and animal form, now that he looked back upon the moment. He didn't know much about rats. He'd learnt about them since, desperately trying to find some redeeming feature within himself. Rats are shy. Well that was hardly a positive, was it? Scavengers. He supposed he could stretch that to 'resourceful' if he tried hard enough? Actually very clean. Peter had hoped for a little more encouragement than good personal hygiene (and, anyway, he didn't consider himself to be particularly clean).
For awhile Peter had considered the prospect that a rat didn't represent his character. Sure, it was undeniable that something as majestic as a stag really did suit James, and something as loyal as a dog fitted Sirius better than Peter could have said... but that didn't mean that Peter was a rat, did it?
Patronuses: James sat upon his desk with that familiar expression of slight arrogance, as his silver stag galloped around the classroom; and Sirius was leant against the wall watching with amusement, his own wand raised and ready (although Sirius always found it much more difficult to think of something happy enough). James's expression of glee increased as Lily's patronus burst from her wand, a sliver doe. A perfect match. Remus was holding back, not wanting his wolf revealed to the rest of the classroom. Peter, too, was choosing not to try very hard – although he suspected he wouldn't be able to master the spell anyway, given it was so notoriously difficult – and was instead glancing around at the others.
There was a silver tom cat, a silver canary and a bright silver tortoise.
The classroom was alive with light.
Peter took a deep breath and summoned up the happiest memory is mind had held onto. He closed his eyes with the effort. He could think of many happy memories: the four of them in shrieking shack, the four of them finally completing the Marauder's Map, the four of them sitting underneath a tree in the grounds... but each one seemed tainted by his own sense of inadequacy. Each memory had festered until Peter recalled feeling unremarkable, left out and ashamed of his own thoughts. A rat.
He finally selected his first night at Hogwarts. Peter had been round faced and chubby, Sirius had been loud to suppress the shockwaves that were trembling though the school after his sorting, Remus had been trying to imagine how much his new friends would hate him after they discovered his secret, and James had been struggling not to appear too arrogant. They had been equal then, new in the school – with the same levels of confidence, and reserve, with years and years of friendship ahead of them.
Peter was so shocked by the fact that he'd managed to produce such a bright silver light that he almost dropped his wand. He didn't, however, and upon widening his eyes noted what he'd already known, deep down. A silver rat – beautiful, still, with its long naked tail twisting behind him.
"Look!" A Hufflepuff girl said to her friend, "Pettigrew's a rat."
More of the class started looking and Peter found his face flushing, his happy resolve lessening, and his patronus – something he should have been so proud of – disappearing with it.
Peter glanced desperately at Sirius, James and Remus. The gaze of many of their classmates was still boring into his skin unpleasantly: he couldn't deal with their mockery anymore than he could deal with his own sense of being insufficient. James was too busy flirting with Evans to notice, but Remus and Sirius exchanged a glance and...
"Oi, Sniverlus! Struggling to find a happy memory?" Sirius, instead of bothering to raise his own wand had addressed the boy with a grin. The stag dissipated into light. The Cat, the canary and the tortoise disappeared. Lily, despite being sat at the desk next to James, was not watching Snape (and her Doe had lost its form slightly, Peter noted).
"Expecto patronum!" Snape said, a malicious look on his features, and then...
Then another doe burst into the room.
Silence, then laughter. Lily looked angry. James shocked. Sirius seemed to almost find the whole thing funny, but not quite. Remus raised one eyebrow curiously.
Peter sat down dejectedly. If Snape, who's head was overflowing with prejudices about blood purity and who Sirius always said was sure to end up as 'one of them' could produce something more beautiful, more fantastic and impressive than Peter ever could..? If Snape's character, which they all always considered as insufferable and disgusting, was a doe? And Peter was a rat...?
There was something terribly prophetic about his character being exposed as a rat, Peter decided as he succumbed to his growing self hatred. He was worse than Snape, worse than any of those Slytherins, Peter was a rat – through and through.
He just wasn't sure why yet.