A/N: I'm a Pettigrew-sympathizer, it's got to be admitted. Also, the title comes from a concept in architecture...
Peter hadn't really know what to think when he first discovered his Animagus form. "Disappointed" might be the right word for the nebulous feeling. It wasn't as if he'd expected to be something impressive, but dammit he'd been hoping. But then Remus had smiled and harped on about how rats were misunderstood creatures and were actually venerated in some parts of India, don't you know. No-one had listened to that bit much. Then James laughed and said being a rat could be fun as it'd mean being able to get to places other people couldn't ("Like the girls' bathrooms," suggested Sirius, forever optimistic and slightly perverted), and that was that.
He had indeed ended up sneaking into the girls' bathrooms but unfortunately it was purely in the name of research. Now James and Sirius had succeeded in their long quest to become Animagi they needed another project to occupy their brilliant but mischief-addled minds. Schoolwork was out of the question, obviously, so they'd decided on making what they were calling the Marauders' Map. So today Peter had run across the floor of the bathroom that wasn't occupied by a weeping, tattletale ghost. It had lead to a chorus of screams that made his tiny rat-ears ring. Once the girls were gone Remus and Sirius had sneaked in and were now taking the measurements of the room. It was more than difficult to do it in rat form, tiny rodent paws were not made for delicate charm work, even if James had cobbled together a device out of chewing gum and bits of string for this stage of the Glorious Four Term Plan. He'd left them to it; he had secret passages to discover.
Scrabbling down a hole to check behind it, brainwaves simple and, well, ratty, he suddenly felt alone and scared. He knew he wasn't technically alone. It's hard to be alone in a school of a thousand adolescents even when you want to be, and even now he could hear the chattering and the footfalls of other students in the corridors. But it wasn't about being technically alone. It was always thrown into sharp focus when he was a rat because he could smell the scents of the stag, dog and wolf on his friends' clothes and in their skin and hair. As much as he adored those three, the smell of such big animals was really unsettling. Plus, it made the difference between him and them even more obvious.
He reached somewhere big enough to turn back into a boy and ended up banging his head on the ceiling and swearing a bit too loud. If this was a secret passageway he'd have to stay in human form to find the entrance and exit - no point putting rat tunnels on the map - and then the others could come along and plot it. They still hadn't worked out how they were going to deal with Dumbledore's office without him getting suspicious, but the Marauders were nothing if not imaginative. There was always the option of the Invisibility Cloak but that had gone into temporary retirement after the floating pie incident.
He crawled through the darkness, trying to get some night-vision back rather than cast up a light, and attempted to suppress the fact the rodent sketchiness and paranoia weren't going away as fast as usual. He hadn't used to be like this, so full of fear. It had always been there but not as strong as this. He wondered if the others were having the same sort of trouble. Did James want to headbutt things? Did Sirius want to chase after small animals - after him? He already humped things, that was no use as a qualitative measure. All the books had said the human personality was supposed to influence the animal, they hadn't said anything about the other way around. Admittedly, he spent more time in his Animagus form than the others did. A rat could do all sorts of things a bout could not and wouldn't be seen by most, whereas a bloody great stag or death-omen-esque dog running around the corridors would be unsubtle even by their standards and would prompt a lot of difficult questions. Yeah, maybe that was it. He could ask Remus, but perhaps he wouldn't understand at all, even though Sirius said he reckoned that even though the werewolf had been forced upon him, the wolf with its pack instincts had always been there.
The tunnel began to widen and he could almost stand up straight, but even as claustrophobia lessened his brain wouldn't shut up. He was tempted to turn into a rat again just so his thoughts would be mere abstract concepts, but he didn't. It skewed his perception of the tunnels, plus it was what had gotten him into this mess in the first place. Except… hadn't he come an Animagus out of fear in the first place, in a twisted sort of a way? It'd been part desire to help Remus and part challenge for James and Sirius, but for him it had been a way to stay close to them, to not get shunned and left out in the cold for being boring.
No. He couldn't think like that. Much better to concern himself with the walls and the search for anything that looked like a human-sized opening, closed and hidden in grime.
He was ready to give up when he spotted it. Long experience of secret passageways had taught him the signs and that slight change in the pattern of the stones was like a beacon to him now. He turned back into a rat and scurried through one of their tunnels near it. It came out next to a portrait of three witches eating cake and his stomach gave a little rat-rumble. Why the hell was he always hungry when he was a rat? He found a hiding place to turn human, scourgified the mess from his robes, and headed back to the Common Room. Hopefully it wouldn't be too full. It was a nice enough Sunday afternoon. Maybe people would be studying outside?
No such luck. When he got to Gryffindor Tower and muttered the password the Common Room was almost full. Oh well.
"Hey guys!" he shouted. A few people stared at him, but the Marauders gave no response. Peter sighed and looked around the room for them, and sighed even harder when he saw them. James was readying himself for another attempt at flirting with Lily, all pacing, hair-messing and sizing up whatever unsuspecting boy she was talking to about schoolwork, and Sirius was trying to distract Remus from his afternoon reading with a steady campaign of elbow-jabbing and general attention-seeking. He went up to the dorms to find his Charms homework. Apparently his report on today's exploring could wait. Even then he wouldn't talk to them about what he'd been thinking. They'd understand the idea behind his worries and give examples from their own worlds of big animals and canine camaraderie, but they wouldn't understand what it meant for him. It would never be enough. Things were changing.