One day, Harry walked into the Transfiguration classroom, ready for the first lecture of the day. Inside, he was the only one in class, except for a tabby cat perched on the professor's table. He approached the cat and gently stroked its head. Glancing around carefully, he softly mewed to the cat, "Who's pet are you? The only cat I know around here is Mrs. Norris. I hardly think any of the other students would have left their cat here."

Suddenly, he heard the startled cat yowl back, "Mr. Potter! I didn't know you could talk to animals!"

Then it was his turn to be surprised, "Professor McGonagall?! I didn't know you could turn into a cat!"

She straightened up, "All shall be explained when your classmates arrive. I assume your ability to talk to animals is a trait from your Godly parent?"

He shrugged, "Among others. Don't worry professor, I won't spoil the surprise. By the way, I wanted to ask, can I trust Madam Pomfrey with my secret? The thing is, when demigods are tired or injured, they usually have items like ambrosia and nectar. We call it food and drink of the gods. Only demigods can have it because of its healing properties, but not too much. Mortals are forbidden because it could incinerate them. Today I barely prevented Ron Weasley from eating a whole lunchbox's worth of ambrosia when he raided my suitcase. I was hoping to keep the ambrosia and nectar with Madam Pomfrey in case of emergencies."

She nodded, "Madam Pomfrey is bound by her Healer's Oath to not reveal any medical secrets. I think it is safe to keep your supplies with her. Also, I appreciate you saving your friend's life."

He nodded and took a seat, and eventually, the rest of the Gryffindors and Hufflepuffs entered. Ron flopped down next to Harry with a sulky expression. He groused, "I still don't get why you didn't let me have those brownies."

Harry glared fiercely, causing the redhead to flinch, "First and foremost, who gave you permission to go through MY luggage and take my stuff without my knowledge! Secondly, those were not brownies. It is a kind of medicinal food from my foster family."

Ron's ear glowed red in embarrassment, "Sorry Harry. I didn't want to steal. I was just so hungry, so I got desperate."

Harry glowered a little, "I forgive you. For now. Don't even think about going through my things without my permission. Or I swear to Hades, I will turn you into a jackalope and set you loose in the Forbidden Forest."

His companion shuddered, those eyes were bloody scary. He had no doubt that Harry could carry out his threat. Changing the subject, he asked, "Hey Harry, where's the professor?"

He shrugged, "She'll probably be along, shortly."

No sooner had he said that, the cat on the table leaped off. In mid-jump, the cat transformed into Professor McGonagall. Naturally, everyone exclaimed in wonder and excitement. Hermione's hand shot up immediately and blurted, "Wow Professor! How did you do that? Can we do it too? What books should read to do it? Do we-"

Next to her, Susan clamped the excitable bookworm's mouth. McGonagall chuckled, "My dear Miss Granger. Do take a breath."

Then her expression grew a little stern, "Also, I would appreciate it if you allowed others a chance to ask questions and answer them. This is actually a request from all the professors. We at Hogwarts wish to see all of our students grow and answer questions. They cannot do that if one student keeps denying them that chance."

The girl turned crimson in embarrassment. McGonagall continued, "As for your questions, I am an Animagus. Yes, you all can do it too-"

She raised a hand to forestall any questions, "However! This will only be taught to you when you are much older. As First-Year students, your magical cores are still developing. An Animagus transformation demands a fairly high and stable magical core. If I'm not mistaken, your cores will be strong enough by the time you are in Fourth Year."

She addressed the class, "Does anyone else have any questions about Animagi?"

A Hufflepuff boy raised his hand, "Yes, Mr Caplan?"

"So, can we all turn into cats?"

The woman's lips twitched, "Actually, you can turn into any animal that you want. However, you are only limited to one animal."

Dean raised his hand, "Professor, if we can turn into any animal, how do we know that our own pets are not Animagi."

She smiled, "Now that… is an excellent question, Mr. Thomas. As for your answer, any Animagi have to register themselves and their Animagus form in the Ministry. Of course, there may be rare cases of un-registered Animagi, but that is what the Aurors are for. As for your 'pets' question, let's conduct a small experiment. Why don't some of you bring your pets, just to satisfy your own curiosity."

Before long, Harry returned with Hedwig nuzzling him. Neville walked in with a surprisingly docile Trevor. Harry did notice that Trevor was a little damp, which explained why he was not trying his Houdini act. Ron also came in, carrying an asleep Scabbers. Ron asked, "Should I wake Scabbers up, professor?"

She waved him off, "That won't be necessary, Mr. Weasley."

With that, she began casting a spell on each pet. As expected, there was no change with them. Even Hedwig turned out to be a normal bird, to Harry's relief. He did not need to know whether one of the Athena campers could turn into owls. Then, the spell washed over Scabbers, and things changed for the dramatic.

A bright glow enveloped the rat and suddenly transformed into a short, portly man with grubby skin, small watery eyes, and a pointed nose. McGonagall was stunned for a second, and the now-awake man took that chance to scramble away. However, her wand flew and she quickly cast a Full-Body-Bind and an Incarcerous Spell. Both hit their target, resulting in the man freezing in place and ropes wrapping around him.

Breathing heavily, she clutched at her table and placed a hand on her heart. Her eyes wandered over the stunned class before she spotted her target. She said, "Miss Bones, Could you please head over to my office and use the Floo to call your aunt?"

Susan scampered out immediately, while McGonagall sent Lavender and Hannah to fetch Percy and the twins. She also sent Seamus to fetch Professor Dumbledore. Meanwhile, Ron looked like he was going to be sick. He raced over to the window and dry-heaved as Harry rubbed his back. The redhead whimpered in shock "Bloody hell! And to think that he shared my bed for years!"

There was a flurry of activity, as Lavender and Hannah returned with a confused Percy and the twins. The next person to enter was a bemused Albus Dumbledore, with Seamus. Finally, Susan came back with an older woman who shared her copper-red hair. The woman wore all black robes and had a monocle on one eye. Along with her were a few aurors, and they all had a look at the bound man.

The woman turned to McGonagall, "What happened here?"

The professor responded, "We were just having a class when this happened. I had just shown them my Animagus form, and they asked all sorts of questions. One of the students asked whether their own pets could be Animagi. One thing led to another, and a rat turned out to be a human being."

"Did the student suspect that the man over there, was an Animagus?"

McGonagall turned to Dean, "Mr. Thomas, did you suspect that somebody's pet was an Animagus?"

The dark-skinned boy shook his head. "No, Ma'am. I just asked because I'm a muggle-born and you had just mentioned that a witch or wizard can take any animal form. So, I was just curious whether people could masquerade as ordinary pets."

The monocled woman nodded, "A perfectly valid question, Mr. Thomas. Thank you for your cooperation. Now, who's pet was this man masquerading as?"

Having recovered, Ron meekly raised his hand. She turned to him, "You're one of Arthur's children?"

He nodded, "Yes Ma'am."

"How long have you had the pet?"

Ron looked at Percy, "Been a long time, Ma'am. I inherited him from my brother, Percy."

Then it was Percy Weasley's turn to be interrogated, "Where and when did you find the rat?"

"It was a month before I was about to go into my First-Year, I found him in the garden in our home. I am currently in my Fifth-Year."

"Five years is an unusually long time for a rat to live. Did that not come off as suspicious?"

"We figured that the rat had some magical properties, contributing to its prolonged life-expectancy."

She nodded, "Understandable. Now, I want to make this very clear, neither you, nor your brother are in any trouble-"

Just then, a voice interrupted her, "Madam Bones!"

It came from Albus Dumbledore, who was busy looking at the bound man. She came over to him and he whispered, "I recognise this man. Its Peter Pettigrew."

Madam Bones looked back at him, startled. She whispered back, "Are you sure? I was under the impression that he died, Black killed him and those 12 Muggles."

"So did I. There is only one way to find out. Would you be opposed to an emergency session in the Wizengamot?"

"Of course not! The sooner we get to the bottom of this, the better."

She turned to the aurors and murmured, "Dawlish, the Headmaster suspects that this man is the late Peter Pettigrew. As the Head of the DMLE, I am authorising a full Veritaserum trial. I want you to check the records for the Black trial, just to corroborate any information that may come up in this trial."

"Yes, Ma'am."

"Vance, I want you, Jones, Robards and Proudfoot to pop over to Azkaban and fetch Black. Tell him that there has been an interesting and unexpected development in his case. Shacklebolt, I want you and Savage to bring Cornelius, and I just want him alone, not Umbridge. Scrimgeour, Williamson, secure the prisoner, you two are with me."

They all split up, and Madam Bones turned to Dumbledore and McGonagall. She said, "Would it be too much to ask the students to accompany us to the Wizengamot Chambers? They are witnesses, after all. This might also sound selfish, but in the event that somebody tries to run interference, they cannot deny so many witnesses."

The two Heads looked at each other before granting permission. As all the students shuffled out, Harry was confused. He murmured to a Hufflepuff next to him, "What's going on, Chiara?"

The silver-haired witch whispered back, "No idea. But I think they want us present, as witnesses."

Several Floo trips later, everyone gathered in the Wizengamot chambers. As the children sat down in the bleachers, a man with pale blonde hair demanded to know what children were doing there. Madam Bones ignored him and waited for everyone to turn up. The last ones to arrive were a red-headed husband-wife duo. Harry guessed that they were Ron, Fred, George and Percy's parents. Before long, the session began.

A man in a green bowler hat demanded pompously, "Why have you called us here, Madam Bones!"

Madam Bones spoke, "Minister Fudge, earlier today, during a Transfiguration class at Hogwarts, we discovered an illegal Animagus. The accused has been hiding with an unsuspecting family for several years. As the Head of the DMLE, I have authorised a full trial via Veritaserum. Bring the prisoner in!"

The man was brought in, restrained, and had the Full-Body-Bind removed. Madam Bones approached the struggling man and stunned him long enough to take out a potion vial with a clear liquid. Meanwhile in the bleachers, Susan explained to Harry and Hermione that Veritaserum was the strongest truth potion in existence.

Madam Bones trickled three drops into the man's open mouth and he sang like a canary.

She ordered, "What is your name?"

The monotone reply came, "Peter Patrick Pettigrew"

That drew a gasp out of everyone. Hannah muttered, "I thought he was dead, that Sirius Black killed him."

"Are you an Animagus?"

"Yes"

"What form?"

"Common brown rat"

"Why did you fake your death"

"I was scared to feel Sirius' wrath, especially after I betrayed the Potters"

There was another audible gasp in the crowd and Harry stiffened up. Instantly, Hannah and Kevin Farrell grabbed his arms, aiming to restrain him. Somehow, Madam Bones maintained a professional attitude, "What do you mean, you betrayed the Potters? Wasn't Black the Secret-Keeper?"

The answer came, "I convinced him to convince the Potters to switch Secret Keepers. Told him to think of it as an elaborate prank on the Death Eaters. Joke's on him, because I betrayed them and pinned the blame on him."

Harry was growling, this malaka was the reason why his mortal parents died at the hands of a megalomaniac with delusions of immortality.

A visibly disgusted Madam Bones said, "One final question. Do you have the Dark Mark?"

He struggled to answer, before choking out, "Yes"

"No further questions."

After being given the antidote, he was taken away. Madam Bones then called out, "Bring out prisoner #24601 Sirius Black for questioning."

At this, Fudge exploded, "What the devil are you up to, woman! Black is a dangerous criminal-"

She cut him off and fixed him with a dry look, "Really Cornelius? You have just heard that the man who Black supposedly killed is not only still alive, but confirmed himself as the real betrayer of the Potters, and a Death Eater. Don't you want to be known as the Minister who corrected a grave injustice?"

He thought for a few seconds, before he was sold on the idea. Fudge waved a dismissive hand, "Carry on then, Madam Bones."

She repeated the same process with Sirius Black.

"State your name for the record"

"Sirius Orion Black"

"You are here because you stand accused of betraying the Potters. How do you plead?"

"Not guilty"

"Are you a Death Eater?"

"No"

"So you don't have the Dark Mark?"

"I would have preferred to cast the Killing Curse on myself rather than take the Dark Mark and betray the Potters."

"Were you the Secret Keeper for the Potter's location?"

"I was, for a while."

She repeated, "For a while?"

"I switched with Peter Pettigrew."

"Why did this not come up during your earlier trial before you were sent to Azkaban?"

"Never had one."

She froze, and the audience were murmuring to each other. Madam Bones then mused, "I shall have to look into that miscarriage of justice, later on. Describe your confrontation with Peter Pettigrew."

"I went to Peter's house to find him. The house was empty and no sign of a struggle. After finding out about James and Lily, I ensured Harry's safety before going after Peter. I tracked him down and confronted him. He went crazy, shouting that I had betrayed them, he cut off his finger and sent a blasting curse, killing the 12 muggles and hit me with an overpowered Cheering Charm. After that, I assume that he transformed into his Animagus form and escaped to the sewers."

She nodded, "That will be all."

With that, the interrogation was over. After a few minutes, the results were finally in. Sirius was declared innocent, while Pettigrew was carted off to Azkaban.

As he waited, Madam Bones walked over, "Just so you know, Harry is here."

He looked at her, eyes shining with hope. Sirius breathed, "He is? Can I see him!"

"First make yourself look presentable. Then I shall take you to him."

A few minutes later, she ushered him into a small room and told him he had five minutes. When he entered, he saw Harry alone in the room, leaning against the wall, waiting for him. Sirius staggered a little before dropping to his knees. He held out his arms, "Harry? Is that you, pup? Merlin's beard! You've grown! I see that you're a Gryffindor, just like me and your mortal parents. Listen, I am so sorry for not taking care of you like I should have. I was too caught up in getting even with the rat for betraying your parents. After I handed you to Hagrid to take you to Dumbledore for safe-keeping, I took off. That slippery little bugger somehow pulled a fast one on me."

Harry gently hugged him and spoke up for the first time, "Mortal parents? I take it you knew of my true parentage? Anyway, I'm so happy you are innocent, Sirius. Although, you had better pray that my mother and the girls don't find out that you prioritised finding Peter over me."

He winced, "Yeah… not my smartest decision. But I was the one who scouted that ritual. I think only me and your Uncle Remus are the only ones who knew. Your father was going to tell Peter on the day that they were attacked. I have to admit, I'm glad he never found out, or he would have promptly scuttled off to his precious Dark Lord."

Harry spoke up, "By the way, do you have a place to live?"

Sirius made a face, "I have an Ancestral Home, but I despise that place."

That was when Harry had a brainwave, "I have an idea! You can stay at Camp! I'll talk to Chiron later"

"Camp? Chiron?"

"Chiron is a centaur and he is best known for training all demigods. If we're being technical, we are all blessed by Hecate. So you should be able to enter Camp Half-Blood. It's a camp for demigods and I've stayed there, whenever I was not living with the Hunters of Artemis. Also, Susan Bones was just telling me horror stories of Azkaban. Zeus knows what on earth those dementors did to you. When you do get there, ask for Lee Fletcher from the Apollo Cabin. He's one of the best healers, though Michael Yew isn't too far off."

At the mention of Zeus, thunder boomed in the sky. Harry winced, before murmuring, "Sorry."

Sirius nodded, "I'll take you up on that. I'd probably go crazy if I keep hearing my dear old mother's portrait screaming about Pureblood ideals."

A minute later, Madam Bones was back and she informed Harry that it was time for him to head back to school.

I really thought of ending the chapter at the Pettigrew reveal. However it would have been way too short, so I included the whole trial scene. I dunno if I've mucked up the trial because its been a while since I've seen the movies or read the books.