A/N: This is my theory on why Wormtail leaked information on the Potter's hideout and why he didn't care so much when Sirius was sent to Azkaban. Also, why James trusted Peter enough to be secret keeper (see last sentence).
Unjustifiable
"Oh, come on, Moony!" moaned Sirius Black, as he tried to catch up with his fellow Marauder, who walked very quickly when he was agitated.
"Listen, Remus, it's not what you think—" James Potter stopped immediately as Remus twisted stiffly to face him.
"The nerve of you two! That was completely unwarranted," he hissed. Breathing deeply, the young werewolf turned back around, continuing his pacing of the Gryffindor common room.
"It's really, honestly not what you think—" began James again.
"Hmm, really? Okay, then, James. Tell me what I'm thinking right now!" Remus glared sharply at his fellow Marauder.
"Well… uh… probably that me and Sirius are terrible prats… who deserve to be punished—"
"You're entirely right; you do need to be punished! But like all the other times that you've committed a wrongdoing, who gets penalized instead?"
"Longbottom's toad?" asked Sirius innocently, as he sprawled himself atop an armchair by the fire.
"Padfoot!" said Remus ferociously, still pacing the room. "Don't imagine I didn't see you slip that pickled newt into Peter's cauldron! You're just as guilty as Prongs!"
"Aw, come on, Moony," started Sirius again.
"Come on? Come on to what, Padfoot? God forbid, I have a right to know!" said Remus loudly, stopping in front of Sirius' chair.
"We were just having a little fun, Remus," said James calmly.
"Ah, yes, fun," repeated Remus angrily, his face inches from Black's. "Go ahead and have your fun." He stepped away from Sirius. "But I won't be any part of it." He resumed pacing.
"If you don't agree, Moony," said Sirius, "then just turn us in. You're a prefect after all."
Remus sighed and plopped down in the chair opposite the canine animagus, his hazel eyes regretful and calm once again. "You know I'll never do that, Padfoot."
"I don't understand," said James, also taking a seat, "what did we do wrong?" Remus gazed at the crackling fire contemplatively.
"Do you consider Peter to be your friend?" The inquiry was so unexpected; James and Sirius cast each other stunned glances before responding.
"Yes," said James confidently.
"More or less," replied Sirius.
Remus eyed Sirius appraisingly; so piercing were those hazel eyes, that Black began to feel uncomfortable. "More or less," the werewolf repeated. "Well, he's got to be a reasonably decent friend if the pair of you saw it fit to let him be a Marauder."
"Look, he's our friend," said James impatiently. "What's the deal?"
"The deal," said Lupin, "concerns you playing a prank on your 'friend' today… your best friend. Peter's in detention right now, doing Merlin knows what and it's all your fault."
"Yeah," said Sirius uncaringly, "so?"
"So," replied Lupin, "Wormtail looks up to you two and you're setting a bad example."
"Us three," corrected James.
"You two," repeated Remus again. "Peter and I are just along for the ride. We put our time into helping you guys plan pranks, but in the end, we don't pull them off." Sirius shook his head in the negative at this, while James continued to listen intently. "Look," said Remus, "it's an unspoken fact that Wormtail and I are the lesser members of this group." He leaned forward in his seat. "The only difference between him and I, is that I've figured it out already."
"You're acting like we're dealing with a ten year old kid here, Moony!" Sirius paused, his tone taking on that of a scolding mother. "You're setting a bad example." He quieted at James' scathing expression.
Lupin turned to face Sirius. "It doesn't make a diference how young or old you are, Padfoot! Everyone looks up to somebody; everyone has an idol. Peter just happens to have two heros. And I know that he doesn't idolize you because you inconspicuously play a infinitesimal joke on him every once in a while. Drop a knut into a jar each day, Padfoot, and it's completely full by the end of the year."
"Moony," James began again, but Lupin hadn't finished.
"And how will innocent Wormtail, as you so commonly put it, react when this veiled insight strikes him?" The other boys shrugged. "I've no inner eye," continued Remus, "but I will tell you this: when Peter figures out that you've been taking advantage of him, you'll get a rude awakening."
Looking quite satisfied with himself, the lycanthrope snatched his books from the floor and initiated his walk up the set of steps that led to the boy's dormitory.
"Nah," said Sirius after a lengthy pause, "Wormtail'd never do anything to harm us."
A/N: Please review!