There's no one more fanatical than a convert to a Cause.
Swords of Haven Simon Green
Disclaimer: I own nothing, especially not Harry Potter.
He knows how others see him; his enemies, childhood friends, and even his current compatriots. He is Wormtail, the coward, the rat, and the traitor. What was once a nickname, an alias, has become his identity. He has no pride left; his mind, twisted by living as a rat for over a decade, is dominated by fear and a desperate need to survive. He is a coward because of a rat's instincts, or, perhaps, he becomes a rat because there was always a bit of cowardice in him. Wormtail does not, however, believe he is a traitor. He turned his friends over to his master, yes and knowingly caused their deaths, but he did it for the Cause. Wormtail has never betrayed his Cause.
When he was Peter and the name Wormtail was merely a private joke, he was a Gryffindor; a Marauder. They were the ultimate pranksters and also the favored boys of the school. They knew how to charm all of the teachers, and many of the students, into forgiving them anything. Headmaster Dumbledore chuckled at their antics and occasionally winked at them while proposing mild punishments. Even stern McGonagall smiled slightly even as she admonished them.
Their friendship had started as a bet between James and Sirius–who could pull the most elaborate pranks on the Slytherins and get away with it. Remus, tired of their bragging, or perhaps merely wanting to indulge his own sense of humor, had enlisted Peter's aid in a grand scheme that ended in James and Sirius having plaid rashes for a week. The incident could have started a war between the four dorm-mates, but it had instead forged a strong friendship between them. They became the Marauders, and no one in the school was safe from their pranks.
Peter didn't have the same arrogance as James and Sirius. Both he and Remus stayed in the background more and so managed to get into less trouble. It wasn't, Peter knew, that he wasn't brave or that he was hesitant. He was just more prone to think before he rushed headlong into trouble. Nevertheless, he was still one of the Marauders, full of pranks and daring, kings of Hogwarts.
Things didn't really change until fifth year, when his aunt came to live with his family. Aunt Fernanda wasn't a Squib but she was close. Her best attempts at Transfiguration only managed to change the colors of things; she couldn't change textures at all, much less shapes. Peter hadn't known her very well because she had married a Muggle. He had always felt a little sorry for her, since she couldn't do much magic, and had thought moving to the Muggle world had been a good idea on her part. At least there she wouldn't have to constantly face people who were better than her.
When Aunt Fernanda came to live with them, his mother said it was because she wasn't getting along with her husband. His father had snorted and said that Peter was old enough to know the truth. The Muggle, he explained, had started hurting his wife because he was afraid of her magic. Fernanda didn't tell him she was a witch until after they were married. Everything seemed to be going all right until, two years into the marriage, when his sister was involved in a magical accident. She had fled from the scene by the time wizarding authorities arrived and was nearly hysterical when they tracked her down.
Fernanda had protested, since the woman was related by marriage to a witch, but the wizard in charge said that her hysterical state was too great a risk. She was Obliviated. Fernanda's husband had become paranoid and suspicious, turning on his wife. He became violent, physical strength being the only advantage he felt he had over her.
Fernanda spent most of that summer crying in her room. The only time Peter spoke to her outside the occasional pleasantries, she told him that her husband's memories had been erased. It was better that way, she said, so that he wouldn't be frightened. Then she had broken down, weeping and Peter had hurried off.
When Peter returned to Hogwarts that year, he began his investigations. There were a few Muggle-borns in Gryffindor and he had spent some time talking to them about their families. Lily Evans told him that her parents were proud and happy that their daughter was a witch. Her sister, on the other hand, seemed to hate Lily. Lily told him that it hadn't been like that at first. When Lily had gotten her letter, Petunia, who was a year younger than her, had been as excited as the rest of the family. She had been more subdued the next year. Lily thought it was because Petunia was jealous. Peter thought she was probably right.
Then over the summer of fourth year, Sirius, who was annoyed at being lectured at by the more serious Lily, had sent her a prank package with a boggart inside. Petunia had been the one to open it and she had been terrified. Lily told Peter that she had tried to explain that it was just a malicious prank by an arrogant boy but Petunia hadn't listened. A year later, she still refused to forgive Lily.
Peter also spent time in the library, poring over the many history books, looking for patterns in Muggle-wizard relations. James and Sirius teased him about his new studiousness, but Peter ignored them and they swiftly got bored and moved on to tormenting the Slytherins. Remus was more indulgent and even joined him in the library on occasion. The librarian saw a pattern in the books Peter checked out and he quietly guided the boy to some specific books. Peter was a little shy, but Mister Zabini explained that it's what the librarian was for, to help students find the best books from which to learn and he encouraged Peter to ask him anything.
In History of Magic, the students had brushed over the Dark Ages, the Inquisition, and the Witch burnings. They were told about witches and wizards who laughed at the fires, using charms to escape any pain. The books Peter read told a different story. Adult wizards and witches were perfectly able to escape the Muggles. Children weren't so lucky. A number of Muggleborns were burned along with their entire families. Fourteen Squibs were burned to death. Even a few wizards were killed under various circumstances.
Muggles were not as inferior as people thought they were. Even the people who supported them and said they were equals did so while firmly believing that a Muggle could never really be a threat to a wizard. But Peter knew better. Aunt Fernanda's husband had been able to hurt her. She was a weak witch, but she was still a witch and she hadn't been able to stop her Muggle husband from hurting her. Hundreds of years ago, Muggles had managed to hurt wizards. Peter knew things had changed since then. Muggles then hadn't had all the strange things Lily talked about; things that could make them even more dangerous.
So Peter did more research. He found Muggle books, history books, science books, and managed to acquire some Muggle newspapers. He read about machine guns and wondered if a shield designed to protect against spells would protect against bullets. He read about nuclear weapons and wondered if the wards surrounding Hogwarts would be able to stand against such massive, physical destruction. He compared the population of the wizarding world to the Muggle population and wondered if even a wizard as powerful as Dumbledore would be capable of standing alone against tens of thousands of Muggles.
By the end of the year, Peter could see that Muggles were a threat to everything he held dear. Muggles were prone to jealousy, fear, and hatred. They were incapable of magic but were rather good at creating massive damage through violence. He couldn't see how Muggle and wizard relations could ever end in anything but the destruction or complete domination of one side or the other.
He continued to study history and he found other things that weren't taught to students. Dark wizards who had done incredible things for their world. Most shields and wards were designed by Dark wizards and so were an incredible number of healing spells and potions. A myth about the creation of the Killing Curse, which said that a kind God had shown it to a man that he might painlessly end his love's torment at the hands of a sadistic cult. Knowing Remus–the Werewolf– Peter also knew that not all Dark Creatures were inherently evil. Peter began to believe that the Dark Arts weren't all inherently evil.
In his last two years at Hogwarts, Peter watched as his Gryffindor friends firmly made their stands as supporters of the Light. He tried, occasionally, to make them think about some of the things he had learned, but they dismissed his ideas. He gave up eventually. James was too arrogant to listen to anything that contradicted his viewpoint. Remus was too wrapped up in his problems. Peter didn't even really try with Sirius either.
When the Marauders had mastered their Animagus forms, the relationship between Peter and Sirius had changed dramatically. Sirius, who had rather large teeth as a dog, often snapped at Peter. It was a joke, like most things Sirius did, but Peter was terrified, frozen by his strong rat's instincts. Once he got over the initial terror, Peter was still afraid. Sirius had a temper. What if one day he was angry at Peter and forgot to be careful? Peter had nightmares about those long, sharp teeth ravaging his small, furry body.
It was worthless to try and complain about Sirius to the other Marauders. Remus was sympathetic, but he didn't really understand and he dismissed it as just being the way Sirius was. James only laughed and said it was just a joke. Peter had smiled tightly and gone to the library. He spent much of his time at the library and made friends with some of the Ravenclaws who were always there. He found many of them were very accepting of his new ideas about Muggles. He talked to them about his research and they introduced him to even more sources that shored up his beliefs. One day, Hestia Zabini, the librarian's niece, introduced him to the Cause.
He threw himself into the Cause wholeheartedly. He was wary when he learned Slytherins were a part of it, but Hestia dismissed it as House prejudice and started to try to let it go. Dark was not the same as evil and if they were the only ones able to see the danger they all were in, then he would help them protect everyone. At least, that's how he felt when he was around people who were a part of the Cause. Everything always seemed less clear when he spent time with the Marauders. They were so vehemently on the other side and they had been his closest friends for a very long time.
He didn't meet Tom Riddle until after school. Tom was a handsome man with a silver tongue. He wiped any doubts Peter had about what he was doing completely out of his mind. Peter was alight with the fire of passion, ready to anything for the Cause. The ends would justify the means in time. He only wished his friends could see that.
He was devastated when James became one of the front-line supporters of the Light side. He didn't want to be on the opposite side of a war from his friend. But he steeled himself. It was for James' own good. He would be better off when Voldemort won.
Then James made Peter his Secret Keeper. Peter was surprised that Sirius and James suspected Remus of being a spy. He accepted the position and hurried to tell Tom. He hoped that they could leave James alone, since he had gone in hiding and couldn't actively fight the Cause. He didn't want to be responsible for the death of a friend. In the end though, Tom convinced him. James was a menace to the wizarding world as a whole. He meant well, but in the end his ways would destroy everything. It was a necessary sacrifice to the Cause and Peter mourned it even as he made it happen.
Making the plans to implicate Sirius had been easier. Sirius, Peter felt, was a bit of a mad dog and it was obvious he would never be convinced of the rightness of the Cause. After all, he had betrayed his own family to support the Muggle-lovers. It was better to get him out of the way and he had made it so easy by pretending to be James' Secret Keeper. Besides, being "dead" would give Peter ample room to move about as a spy. He didn't learn of Tom's defeat until days later. He almost gave up in despair, but his spirits rallied as any Gryffindor's would have. It was only a battle lost, not the war. The Cause would never die.
It would have been easy for Peter to disappear. No one was looking for him. He was, after all, dead. Who would think to look for a dead man? The only people who would recognize him were in Britain and Britain is a rather small island in a big world. But Peter was loyal to his Cause. He stayed a rat and attached himself to one of the strongest wizarding families for the Light. When the war returned, the Weasely's would be among the first to know. He prepared himself for the day when he would again be able to serve the Cause.
As the years passed, human intellect sunk below the surface of animal brain. By the time Wormtail regained human form, his passion and loyalty for his Cause had been subsumed by his instinct for survival. He still believes, completely and without doubt, but he no longer wants to be in the front-line. He had been eager to be the hero before, to show up Sirius and even James, but now he would be content simply to make the world better. However, things have changed. Tom Riddle had been a charismatic champion for the Cause, but he died years ago. All that is left is the insane egomaniac, Lord Voldemort. Wormtail serves him out of fear as much as anything.
Still, there are sparks of bravery in him. Wormtail could have disappeared in Egypt. He knew the Dark Lord was returning, knew the war would start again, knew that he might die in it. He is more rat than man now, but something stopped him from jumping ship when he had the chance.
Yes, Wormtail is a coward. But he is a coward who believes in his cause. Who knows what kind of bravery that might lead him to.