I do not own Harry Potter. Charlotte Potter is my OC.

The Rat

Snape thrust Charlie's Invisibility Cloak aside and Harry shot her a look that clearly said 'thanks a lot'. The raven-haired girl shrugged helplessly and turned her attention back to her Potions professor. He looked positively delighted, but in a sadistic sort of way that made dread curl in Charlie's stomach.

"Snape," Black growled. "What are you doing here?"

A cruel smile curled across Snape's sallow face. "I was on my way to deliver your potion, Lupin, when I ran into a terrified Hermione Granger. She told me a black dog had taken Mr. Weasley through the passageway of the Whomping Willow. She tried seeking your assistance but you weren't in your office. When I checked for myself, I found your little map, which confirmed my suspicions."

Remus took a step towards the Potions professor. "Now Severus, you need to—"

"Silence!" Snape snarled, his wand aimed straight at Sirius' chest. They were glaring at each other with complete contempt. "Do not move, or I swear I will do it."

Remus cautiously moved back with his hands held out in front of him. "Calm down. Sirius has a story to tell and you need to hear it."

"I don't need to hear anything!" Snape snapped. "I know what he did, and I was right about you. Dumbledore wouldn't listen when I told him that you were assisting your good friend Black into the castle. You don't know how much I'm going to enjoy bringing you to the Dementors."

"Are you really going to kill us because of a schoolboy grudge?" Remus demanded.

Snape's eyes gleamed. "Don't tempt me."

Vine-like ropes shot out from the end of his wand and entwined around Remus, bringing him to the ground. Sirius, defenseless without a wand, could only snarl in fury.

Harry was horrified. "What did you do that for?" he cried.

"I can imagine how shocking this must be for you, Mr. Lupin," said Snape softly, his dark eyes staring at the two men with triumph. "A whole life undone by one night of lies."

"He's not a liar!" said Harry furiously. "You've been out for him since the very beginning!"

"And you know exactly why!"

Charlie clamped onto Harry's wrist and shook her head warningly. "Professor," she said carefully. "Um, I'm not sure if you heard, but there's a possibility that Ron's rat might be—"

"I'm disappointed in you, Miss Potter," Snape said, never taking his eyes off Sirius. "To so willingly accept their pitiful stories. I hope you see, now, that your father and his little friends were disgusting and vile."

Charlie was aware this was said to get a rise out of Black rather than her, although she didn't appreciate it regardless. Sirius' lips peeled back and he bared his teeth. "I should have expected you would still be a plague on Hogwarts."

Charlie's eyes flicked to the floor. Remus had been unable to keep his grip on their wands when Snape attacked him and they were scattered near his body. "Professor," she said slowly. "I'm just going to get my wand back."

But Snape didn't seem to have heard her. He was breathing hard, his eyes narrowed into slits. "I'll bring you to the Dementors myself, Black."

"You can't!" exploded Sirius. "The truth must be known!"

"The truth is known," growled Snape. "You're nothing more than a criminal, Lupin is a monster, Pettigrew was a stupid coward and Potter was an arrogant and worthless Gryffindor."

He was not worthless! thought Charlie furiously.

Snape was thrown backwards and he hit the wall hard. He slumped to the ground, unconscious. Charlie stilled for a second before frantically running to his side and shaking his shoulder. "Professor Snape!"

"You did it again!" cried Ron.

Sirius was astounded. "How…how did you do that?"

"I unleash magic accidentally when I get angry," said Charlie, staring at the prone form of Snape in dismay.

"Get your wands back," ordered Sirius.

Charlie seized the wands and distributed them to her friends. Harry hurried over to Remus and removed him from the bindings.

"Is there a way to tell?" she asked, returning the conversation to its original topic before Snape had interrupted. "If Scabbers is really Peter Pettigrew?"

"There is," said Sirius. "And I'm getting tired of waiting."

"But I don't understand how you knew Scabbers was with me," said Ron.

Sirius reached into his shirt pocket and pulled out a crumpled-up newspaper clipping. "During one of Fudge's inspections, he gave me a copy of the Daily Prophet. I was closed off from the outside world and took whatever news I could. That's when I spotted this."

He handed the clipping over and Charlie took it. Harry peered over her shoulder and gasped. "Hey! It's the picture of the Weasleys in Egypt!"

"What?" Ron cried, trying to sit up as best he could. Charlie passed him the black and white picture and the ginger stared at it in shock. Sure enough, it was the same picture he had sent to his friends during the summer. And there was Scabbers, perched on his shoulder. "But how could you have possibly known this rat was Peter Pettigrew?"

Sirius' eyes narrowed. "I've seen Peter transform many times. I knew it was him instantly. The caption said the boy would be returning to Hogwarts. I knew that's where you were, Charlotte." He seemed like he wanted to say something else, but refrained from doing so. "And take a close look at the picture—the rat is missing a toe."

Ron snorted. "He's always had a missing toe."

"They found Peter Pettigrew's finger at the scene," said Charlie, her stomach starting to turn with disgust. "Did…did he cut it off himself?"

Sirius nodded. "Right before he blew up the street with the wand behind his back. He transformed and went into the sewers, where he began his life as the rat he really is."

"How come you were muttering 'Hogwarts' and 'Potter' in your sleep?" asked Charlie in confusion. "That's why everyone thought you were coming to kill me when you escaped."

Sirius looked surprised. "I didn't know I was talking in my sleep. I managed to keep a hold on some of my sanity, but I lost a good chunk of it. Hard not to when you're in there. I suppose I was worried Pettigrew might try to hurt you eventually."

"How is it possible to keep your sanity in Azkaban?" asked Harry curiously.

Sirius smiled grimly. "I knew I was innocent. That thought wasn't a happy one, and so the Dementors couldn't take it from me. The knowledge that I was innocent kept me sane."

"Why did you want Pettigrew to be the Secret-Keeper?" asked Charlie

Sirius' eyes turned bright. "I thought Voldemort wouldn't even think about going after Peter. He wasn't an obvious choice. Peter agreed, and it took some convincing, but James agreed as well. On that fateful Halloween night, I went to check on Peter at his hiding place, but he was gone, and there were no signs that he had been dragged off. By the time I got to Godric's Hollow, it was too late. None of us could have ever guessed Peter would turn to the Dark."

The prophecy.

It came to the front of her mind with full force and Charlie snapped her gaze to the squirming rat. Perhaps it hadn't ever been about Sirius Black. If Scabbers really was Peter Pettigrew, and Voldemort's servant was going to return to him before midnight…

What time is it?!

"How did you get into Gryffindor Tower?" asked Ron suspiciously, barely pulling Charlie from her frantic thoughts.

Sirius patted Crookshanks on the head. "I'm not sure if you're aware, but this cat is half-Kneazle, and is extraordinarily intelligent. He knew what Peter was from the moment he laid eyes on him. When he met me, he knew I was also an Animagus. It took a while, but I gained his trust. He stole a sheet of passwords."

Ron looked outraged. "Wait a minute! You stabbed me in the shoulder that night!"

Harry rolled his eyes. "You know, that should have been the first thing you brought up."

"Shut up! You didn't say anything!"

"I'm not the one who was stabbed!"

Sirius was apologetic. "And I am very sorry about that. You awoke suddenly and scared the Merlin out of me with your scream. I accidentally dropped the knife I was going to use to kill Pettigrew and it unluckily landed right in your shoulder. I needed to get out of there, so I ran."

"I scared the Merlin out of you?" Ron asked incredulously.

"Ron," Remus cut in, holding out his hand. "The rat, if you please."

Ron frowned. "Are you going to kill him?"

"Yes."

"No." Remus glared at Sirius. "We're just going to cast a spell on him. If he's a regular rat, we apologize for all of this. If he's really Pettigrew, then yes, we'll kill him."

After a moment's thought, Ron held out the rat, which was thrashing in his grip. Sirius and Remus raised their wands and cast a spell. Ron dropped Scabbers in surprise when he started to convulse. Charlie and Harry clung to each other and watched with wide eyes as the rat turned into a small man with watery eyes and a pointed nose.

"Merlin," Ron croaked.

Remus smiled a dangerous smile. "Hello, Peter. It's been a while."

"My friends," Peter Pettigrew rasped, but he made no move to get near them.

"Now, I don't know if you've been paying attention or not, but I have a few questions for you," Remus said pleasantly.

"Surely you're not going to believe Sirius! He killed Lily and James, Remus!" Peter cried.

Sirius snarled and Remus held him back. "Then why, Peter, have you been living as a rat for twelve years?"

"I knew he was going to kill me! I exposed him. It was only a matter of time and I was scared!"

"You knew Sirius would escape from jail when no one else has ever done it before?" Remus asked with an arched eyebrow. "I find that difficult to believe."

"Mr. Black?"

Sirius jumped. He was obviously not used to being addressed in such a manner. He turned to face Harry, who was staring at Peter in shock. "Yes?"

Harry glanced at him. "How did you escape from Azkaban?"

"He used Dark Magic, of course! Tricks learned from—"

"He was asking me," Sirius growled and Peter went silent. "Like I said before, I kept my sanity knowing I was innocent. But what gave me strength came from knowing that Pettigrew was in Hogwarts. After I saw that picture, it was like a fire had been lit within me. The Dementors couldn't put it out, and I was worried that he might attempt to harm Charlotte to get in good with Voldemort's supporters."

"That's a lie!" Peter said shrilly. "If anything, I was hiding from the Dark Lord's supporters because I cost them their best spy!"

Sirius' left eye twitched. "You know, I'm surprised I didn't peg you as a spy from the start. You always liked hanging around friends who could protect you."

"Sirius," Remus cut in. "You can deal with him later."

Sirius nodded and took a deep breath to calm himself. "The Dementors can't see, so I turned into a dog one night when they were bringing me food. Animal emotions are different from human emotions and that confused them. I squeezed through the bars and swam to the mainland."

Harry bit his lip. "But why hasn't he killed Charlie? He's had plenty of opportunities."

"You see?" Peter cried. "I haven't harmed a hair on that girl's head."

"That's because you never do anything for yourself!" Sirius bellowed. "You've always done what others tell you to do! And you would never dare to murder under Albus Dumbledore. You were keeping an ear out, wondering if your old master would return to power and if it was safe to join him." Sirius turned to face Charlie. "I would never have betrayed Lily and James," he said thickly. "I loved them."

"I know," she said quietly.

Sirius smiled at her, relief on his features, before glowering darkly as Peter dropped to his knees in horror. "I think it's time we settled this once and for all."

"Of course." Remus rolled up his sleeves. "Sirius, I am deeply sorry for believing you were a spy."

"Forgiven. Please forgive me for not telling you we switched Secret-Keepers."

"Forgiven."

And as the two men advanced towards Peter, Charlie knew there would be no forgiveness for him.

The man crawled desperately over to Ron. "Kind master, please don't let them do it!" He latched onto Ron's leg and the ginger gasped in pain.

"Get your hands off of him," Remus thundered. "And if you even lay a finger on Harry or Charlotte, your death will be as painful as we can make it."

Peter cowered against the floor. Charlie stared at him, at the rampant fear in his eyes. It had been him all along. He'd been free, or as free as he could be as a rat, for twelve years while an innocent man rotted. He was the reason her parents were dead, why she had to grow up without Harry, and without a godfather. If she let them kill him, there was no way Peter would be able to rejoin Voldemort. The prophecy wouldn't be fulfilled.

But as their wands raised Charlie lunged forwards, planting herself protectively in front of him. "I can't," she said. "I can't let you kill him."

Sirius and Remus looked at her in disbelief. "He killed your parents," Sirius protested. "You're standing up for him?"

"I don't want you two to go to jail for murder," Charlie explained. "Sirius, you're still a wanted man. No one will believe the words of three teenagers and your best friend. We need him to prove that you are innocent. My parents wouldn't have wanted their two best friends to become murderers. And…and I don't believe two wrongs make a right. Pettigrew did a horrible thing, but that doesn't mean we have to do the same."

Sirius stared at her for a long moment. "You're a kind girl, Charlotte. Are you sure this is what you want?"

Charlie nodded. "He can spend the rest of his life in Azkaban. And you can call me Charlie, if you want."

"Thank you," whimpered Peter. "Thank you."

"Don't thank me," said Charlie with a frown. "I don't need your gratitude."

Remus started forward and used his wand to tie Peter up. "If you even think about transforming, we will kill you," he threatened.

Peter was face-down, gagged and bound. Remus stepped over him and wrapped Harry up in a hug, which he had wanted to do since the moment he stepped foot in the Shrieking Shack. Harry clung to him in relief. Remus pulled away after a moment and hurried over to Ron. "How are you doing?"

Ron's face was white with agony. "My rat was actually a murderer, and I've shared my bed with him. What do you think?"

"Fair enough. I'm not as good as Madam Pomfrey, but perhaps I can strap your leg up until we get you to the infirmary."

Some ropes shot out from the tip of his wand and curled around Ron's damaged leg, making a splint. Ron cautiously got off the bed and hobbled on one foot.

Snape was still unconscious. Charlie inwardly flinched, dreading the reaction he would have once he woke up. "We'll have to carry Snape back to the castle."

She stuck his wand into his pocket before casting the Levitation Charm on him. Ron and Remus chained themselves to Peter so he wouldn't get away. Crookshanks, looking rather smug, led the trek back through the passage.

Sirius and Charlie were at the back of the group. He turned to her and he said, somewhat earnestly, "Charlie...I don't know if anyone told you this, but I'm your godfather."

Charlie felt her lips twitch as she recalled the first disastrous trip to Hogsmeade. "I may have heard something about that."

"Well, your parents appointed me your guardian should anything happen to them," Sirius said carefully. "I'll understand if you want to stay with your aunt and uncle, but...when my name gets cleared, you could come live with me...if you wanted to."

Charlie gaped at him. "Really?" she asked joyfully. "When can I move in? Where do you live?"

"You really want to come live with me?" Sirius asked hopefully.

"Yes!"

A delighted smile broke across Sirius' face. They soon reached the end of the tunnel and Crookshanks scampered out to touch the knot in the tree. Everyone clambered outside and stood in the middle of the dark grounds, the only light coming from the castle ahead.

"Charlie! Ron! Harry!"

"Hermione?" Charlie asked incredulously, watching the girl climb shakily to her feet.

"What are you doing out here?" demanded Remus.

"I tried to—but the Whomping Willow—couldn't get past—have the goblet—it's a full moon tonight!"

As if fate were laughing at them, the clouds chose to part at that moment, revealing a bright, silver, full moon.

Why me?

Sirius flung out an arm, stopping Harry and Charlie from moving forwards. Remus had gone rigid, his limbs jerking wildly.

"Hermione!" he barked. "Get over here now!"

Hermione dropped the goblet and sprinted over to them, white-faced and absolutely covered in scratches. "Is that—"

"Yes, it's Sirius Black, but he is not who we have to worry about right now," said Charlie in a rush.

"Oh no," Harry whispered in horror. "He hasn't taken his potion!"

"I tried," wheezed Hermione, running on her last shreds of energy. "But I couldn't—"

"Don't talk, run!" ordered Sirius.

"But Ron—" started Charlie.

"I'll help him! Go now! Do not separate!"

In a second Sirius had turned into his dog form. Charlie, Harry and Hermione didn't move, transfixed by Remus' transformation. His body lengthened and his teeth grew incredibly sharp, and in seconds he was a full werewolf. He ripped from his bindings with ease and Sirius lunged himself at him, tackling him to the ground.

"Ron!" Harry cried suddenly.

Charlie shrieked as Pettigrew jumped for Remus' dropped wand. Ron tried to get it before he did but his bad leg slowed him down. There was a flash of light and Ron crumpled. Crookshanks launched for Pettigrew's face but another spell sent the cat flying.

"Ron! Crookshanks!" screamed Hermione.

"Expelliarmus!" hollered Charlie.

Remus' wand flew into her possession. Pettigrew transformed, turning into the form they once knew as Scabbers, and he scampered through the tall grass, disappearing from sight. Remus grabbed Sirius by the neck and tossed him away before running into the Forbidden Forest. Sirius stood, bleeding heavily, and ran after him.

The kids ran over to Ron. "Ron!" cried Harry. "Can you hear me?"

There was no response. His eyes were glassy, but he was breathing.

"Ron's fine," Charlie said with immense relief. "I don't know what Pettigrew hit him with, but he seems to be fine." She glanced around and spotted Crookshanks sprinting towards the castle. "Your cat is fine, Hermione." Her gaze travelled to Snape, who was still levitating above the ground with his eyes closed. "Professor Snape is fine."

"Well, Uncle Remus and Sirius aren't fine! What do we do?" Harry asked anxiously.

Charlie pressed a hand against her forehead. "Okay, we're going to the castle. We'll get help—"

A pained bark echoed across the grounds. Charlie froze and glanced at Harry. "I don't know if we have time for that," he said.

"Then we follow them," said Charlie determinedly. "Come on!"

They took off towards the sounds of howling and barking. When they reached the body of dark water, they came to an abrupt halt. Sirius was back in his human form, curled up in a tight ball against the ground. At least a hundred Dementors were swarming towards him and Charlie felt like she had stepped into Antarctica, it was so cold.

"Think happy thoughts!" she ordered. "The incantation is Expecto patronum!"

I'm going to go live with Sirius. I'll get to escape the Dursleys.

The Dementors were coming closer. Sirius was defenseless. Harry and Hermione tried the incantation, but their wands were silent.

"Expecto patronum!"

A feeble silver mist escaped her wand. Charlie gulped as the Dementors formed a wall around them. Harry and Hermione fainted. Screams echoed in her head, and the fog grew thicker...she was freezing...

"EXPECTO PATRONUM!" she cried, dropping to her knees in the cold grass.

Sirius is innocent...I can live with him...

As she raised her wand for a final try, a Dementor moved closer to her. A slimy hand reached out from under its cloak. It reached up and removed its hood. There were no eyes, just grey, scabbed-over skin, and a gaping black hole for a mouth.

The desire to vomit hit her strongly. She was frozen with disgust and fear. Her wand clattered to her side as the screams of her mother and father got louder. She screwed her eyes shut and raised her hands to guard her face.

Just as the fog threatened to consume her there was a bright flash. A silver glow danced in front of her closed eyelids. Slowly she opened them to see the lake being illuminated with a brilliant light. The cold was ebbing away and the screaming stopped. Sick and trembling, Charlie glanced around. She caught sight of what looked like a silver unicorn galloping back across the water and the Dementors retreating. She climbed shakily to her feet, stumbling to check on her friends and Sirius. They were out cold, but the Dementors hadn't gotten to them.

She looked across the lake to see a slender female reach up to pet the unicorn.

Her legs gave out and the darkness engulfed her.