Convincing McGonagall was a lot simpler than it would have been. He remembers back in First Year when they tried to convince her of the Stone, but she refused. He grins sharply, if he'd known this was the solution to make her believe him, he would have died years ago! (He doesn't say that out loud though, McGonagall would have a stroke, she doesn't appreciate his puns very much.)
He had left Sirius in the kitchens, asking the Elves kindly to supply a bath for Sirius, and took the direct route to the Great Hall (through the walls), which consequently meant he terrified a few students by suddenly appearing.
Most of the other ghosts were in the hall, floating about and being very in the spirit of Halloween, (he giggled to himself for that pun), and the Hall was loud in raucous cheer and Halloween themed treats and pumpkins.
He shot only somewhat leisurely over the head of the students getting a chorus of 'hellos' and waves from some of his year mates and the lower years, which he answered with a smile. It was funny, he was far more appreciative of the game this gave him, over him being The-Boy-Who-Lived, it was more to do with the fact that it alleviated most of his boredom to talk to everyone.
Coming to a stop next to McGonagall, he smiled at Snape and Dumbledore. Dumbledore smiles back enthusiastically, and Harry noticed he had a small pot of lemon hard candy next to him, did he go anywhere without it? Harry decided he would make that his mission for the year, figuring that out, much less dangerous than basilisks and Dark Lords.
Snape sneered back at him, though it had less venom in it than it did before, "you might be a ghost, Potter, but that doesn't mean you're allowed to interrupt our dinners".
"Severus, really", McGonagall tutted at him, and Snape harrumphed in return, taking a swig of pumpkin juice that certainly did not smell alcohol free, though Harry just smiled strongly in return. He knew that Snape really did enjoy his persona as the Bat of the Dungeons, and went far to keep it that way.
He turned to McGonagall, "Professor! I need to speak to you. In private!".
"Can it not be said here, child?" Dumbledore spoke, having obviously any objections about interrupting a conversation that doesn't include him. Harry kept that in mind.
"Well… if could, but it's information on where Sirius Black is, and I don't know if the student population should hear it.." he trailed off awkwardly, twisting his fingers. The teachers face dropped.
"You know where that mutt is?" Snape spat, "you must tell us at once!"
"I'll have you know I think he's more of a Irish Wolfhound," Harry retorted, "a pure one at that".
Snape seemed to double take at Harry's knowledge of dogs, and arched an eyebrow. "My Aunt Marge is a dog breeder!" He said in defense.
"Just tell us where he is. Dunderhead." He muttered the last bit.
McGonagall has stood up in the meantime, placing her napkin on her plate and placing the chair underneath the table, "We must go at once, to my office I think. Of course Albus will accompany us, and Snape too, as he's already involved," she said primly, and waited for the others to do the same. Once they did, they moved off together, McGonagall taking the lead.
"I must know, Harry," Dumbledore popped a lemon sweet in his mouth as they moved through the corridors, "why you wanted to tell McGonagall, and not me."
"Well, McGonagall is a Transfiguration Professor," he replied easily.
"You realise, I was also a Transfiguration Professor, my boy?"
"Ye-es, but I needed someone who is excellent at Transfiguration," beside Harry came a choking noise, but when he glanced at Snape, his face was still deadpan.
Dumbledore just coughed, "I am not one for self-aggrandisement," he ignored the "yes,l you are", from McGonagall", "but you know I am the most powerful wizard on Earth at this moment?"
Harry answered back obliviously, "I'm sure you are, Professor. I'm also sure you didn't defeat Grindlewald by turning a pig into a desk."
Snape couldn't hold back a laugh at that one, and Dumbledore actually coughed so hard, he spat out his lemon drop, "I suppose that's true…"
All too soon, they were at McGonagall's office, and the Professor in question turned around to face Harry, "Where do you think he is, Harry?"
"I'm not telling you."
The Scottish lady looked as if steam were going to erupt from her ears, and Snape's face showed nothing but derision, "then why-"
"I'm not going to tell you, unless you put a spell on Scabbers".
"The Weasley rat?" Snape spat out disbelievingly.
Harry nodded, "Yep! Then I'll tell you exactly where he is and how to get to him."
"And how exactly do you know where he is?" Dumbledore asked, nonplussed at this whole situation, and if he didn't know better, Harry would say he was enjoying this situation.
"I bumped into him in the halls, he was a bit surprised to see me like this," he gestured to his ghostly figure.
Snape slapped his forehead with the palm of his hand, "And you didn't think to tell anyone immediately and get yourself out of there! Idiot child!" He hissed.
"What was he going to do to me!" Harry replied indignantly, "I'm already dead!"
There was silence after that, until McGonagall said with a resigned air, "Dipsy."
Harry turned his head to look at her confusedly, until there was a pop and an elf appeared, "Yes, Ma'am?"
"Could you please find Scabbers, Mister Weasley's pet fat and bring him to us?" She commanded.
"Yes, Ma'am", she bowed and apparated, not even hesitating at the odd request.
Now they are waiting in silence for Dipsy to appear again.
"The spell I want you to use is…" Harry pauses, thinking of the correct pronunciation, ignoring the way they jumped at the sudden noise and Snape's glare towards him, "ut reditus hominum." He nods, "yep! ut reditus hominum."
McGonagall stares at him, "the Animagus Reversal spell?"
"You can't back out now!" Harry returns, "You promised!"
"She did no such thing," Snape growls, "why do you want Minerva to cast that on the rat?"
"Isn't it obvious," Harry starts with heavy sarcasm, to be cut off by Dumbledore.
"It would seem, the young Mr Potter believes Scabbers to be a human in Animagus form. Is that right? Would you like to tell us who?", Dumbledore looks at Harry over his glasses, eyes twinkling, and Harry suspects that he already knows.
"And ruin the surprise?" Harry grins, this is the most fun he's had in ages, the context of which is slightly horrific if you truly thought about it. Getting his former teachers to guess that Scabbers is truly his parents murderer, but recalling his conversation with his parents, he realises that he has come to terms with it. Death is funny that way.
"Potter", Snape warns, but just at that moment Dipsy appears, hands full with a struggling rat, whose writhing returns in vigour when he realises who he's facing.
"Just place him on the table please, Dipsy." Dipsy did so, holding him in place.
McGonagall stares at Harry, "are you sure?" And when Harry nods back in earnest, speaks the spell.
The light blue light shoots out and hits the rat, the change is sudden and somewhat disgusting, and all too soon there is a hunched man with a disgusting smell and little clothing in Dipsy's grasp, holding still in shock.
"I can't believe he was right!" Harry laughed, well, he did but that's besides the point. "Everyone, this is Peter Pettigrew, my parents murderer." Everyone stays silent, even Dumbledore hadn't actually predicted this one correctly, "look at his hand! Harry reaches out and touches one of his arms, and Pettigrew held it out on reflex, where he shows a missing finger.
"You mean to tell us you didn't actually know whether Black was telling the truth?!" Snape moves first, casting a petrificus totalus before the man could move. "That could have all been a trick!"
"But it wasn't!" Harry retorts.
"But it could have been!"
"But it wasn't".
Snape presses his fingers around the bridge of his nose, "Foolish boy".
"Foolish ghost," Harry corrects.
Snape takes a breath but Dumbledore speaks first, "Boys, I think we have more pressing matters to absolve, yes?"
Ropes now bind Pettigrew and the petrificus totalus spell taken off. The rat like man, (Harry didn't know if he naturally looked like the fat mouse from the Great Mouse Detective, or if it was from the years he spent as a rat Animagus, but it was definitely a look), was quivering and blubbering out how it was all Sirius.
McGonagall has begun to question him, her eyes shiny and voice tight with fury, questions along the lines of, "if it was Sirius that killed them, then why did you make us believe that he had killed you? Why did you cut off your finger?"
The answers Peter have in return sounded like complete bullshit in Harry's opinion.
In the meantime, she had held up her side of the deal, so it was time to uphold his, "So, now you all agree that Sirius isn't actually responsible for all the crimes held against him-"
"Some of the crimes," Snape mutters.
"- I can tell you… he's in the kitchens!" He announces like he wasn't interrupted.
"The kitchens, you say? Dipsy, if you would be ever so kind as to bring Sirius Black up from the kitchens please," Dumbledore pops another lemon drop into his mouth and relaxes in a chair.
"He was in the kitchens?" The Potions Professor dead-pans, "He was in the kitchens?"
"No, I took him to the kitchens, he was on his way to the Gryffindor Tower. What!" He replies in turn to Snape's glare, "He looked hungry!"
"And I was hungry," Sirius in turn butts in, looking only slightly scared to be in front of Dumbledore, "Good to see you too, Snivellus".
"How was your stay in Azkaban, mutt-"
"I told you! Not a mutt!" Harry says, annoyed.
"-I have to say, you look slightly less deranged than I thought you would."
And it's true, now he's clean, and apparently wearing a largened version of the plain Hogwarts Robes, he looks almost like a functioning member of society. There might be a glint of craziness in his eyes, and he's got a faintness about him that makes him look similar to Snape-
Omg they look almost identical.
Both with long lanky dark hair, pale waxy skin, both due to lack of sunlight, (one to Azkaban, one to most time spent in Dungeons), both dressed in complete black with tall gaunt features. They look like siblings.
It starts with a giggle, one that he hurriedly tries to stifle it, but turns into full blown laughter, and as like when Snape discovered him crying, without breath, he can laugh as long as he wants to- or even if he doesn't want to.
"Whatever is the matter?" Dumbledore asks, chortling, for its true that laughter is contagious.
"It's them!" He points at Snape and Sirius, who next to each other, look even more alike than before, both wearing expressions of distaste, "their names both even start with an 'S'!"
It's obvious that they haven't been following his train of thought, not that he can fault them for that, they aren't mind readers, so they all look bewildered at his reaction- even Pettigrew.
"Are you okay?" Snape and Sirius ask at the same time, a sarcastic ring to their voices, and then turn around and glare at each other. Which just sets Harry off further.
Harry just nods and leaves the office, managing out a, "I'm gonna come back later, I'm sure you can sort this out better without me!" Between laughs and heads back to the Gryffindor Common room where he knows everyone will be by now. He also knows it'll be easier for everyone without a literal ghost of their mistakes hovering over them. Besides, he's quite sure that death is making him more loose with emotions. Or maybe just the fact he can't be punished for anything, he's finally let himself loose and have fun. Whatever it is, he's happy with it. It's better than the Dursley's punishments hanging over his head.
He'd love to stay longer and prove Sirius' innocence, but he is, for all intent and purposes, a child, and not actually needed. He's sure they will call the aurors, and the whole thing will be sorted out, and if not, then he will get involved.
Nearing the Gryffindor common room door, he sees the Fat Lady glare at him, "Password."
"I'm not a student anymore! And I'm a ghost, I can just go through you," he points out.
"But it feels awful," she replied, pointing a wine glass at him, "Just say the password!"
"Fine," the ghost sighs, "Post Vita".
The door swings open, and he's assaulted with the loud noise of the common room, filled with its usual chatter.
"Hey guys!" He floats through the common room and settles cross legged in the air next to his friends, "you'll never believe what just happened!"
He fills them in, their jaws dropping and Neville looked like he might faint.
"You made friends with a supposed mass murderer?" Hermione levels him with a look, and suddenly he feels as if he's in deep trouble.
Ron just laughs at him, having that look directed at him way too often. "Can't help you there mate."
"Well, yes.." he stutters out, "but he wasn't a mass murderer you see". Hermione is a lot scarier than Snape, he decides, and he can't wait to tell him that.
"That's not the point! What if he took you too the dementors and stole your soul! What if he took a wand and managed to petrify you, remember Nicholas last year?" She slams her book down on the table, "We already lost you, do you think we want to lose you again?" She stands up and flees to the dormitory.
He winced as he hears a door slam.
"Sorry, mate," Ron says around a mouthful of Pumpkin Pie, "wanna play Gobstones?"
Perfect, amazing Ron, who just went with whatever and was a great friend.
"Sure!"
It turns out ghost vision (which isn't as cool as it sounds) in place of years out of date prescription in his glasses means he has way better depth perception that when he was alive, which means he's amazing at Gobstones.
"Aha!" He exclaims as he wins another round, "that's 3 out of 5 wins for me," he looks around, wishing there was a clock in the common room, "anyone know how much time has passed?"
"About an hour," Ginny supplies, where she's sitting with her friends nearby when he realises no one around him is wearing a watch, "why, where does a ghost need to be?"
Ginny's a good friend too, he's sure that she must have freaked out over the summer, because she went through some trauma that can't be dealt with over night, but she didn't let that stop her from being a great person with a great hand for minor hexes.
"Oh, just providing a hand it capturing Peter Pettigrew and giving him to the dementors! Bye guys!" He waves goodbye and shoots out of the common room, hearing a grumble from the Fat Lady behind him. He rockets straight up, and tight through the walls arriving quickly at McGonagalls and moved through it.
"Hi!"
Pettigrew is gone now, and so is Sirius, as is Dumbledore. McGonagall and Snape are still there however, talking about something between them.
"Where is everyone?" He prompts, settling cross legged at the same height as the chairs. Snape looks at him oddly and imperceptibly shifts his chair away.
"At the Ministry. I gave the mutt some Veritaserum when Kingsley floo'd through, and we got the truth," he shrugs, "it is a wonder why that didn't happen in the first place. Anyway, Kingsley took them through to the Ministry and they're planning for a trial and Sirius' exoneration, Dumbledore went with them".
"So he's gonna be free! Yes!" He grins and noticeably starts bobbing up and down in the air, "are they going to get rid of all the Dementors too? It's not like they need them anymore".
McGonagall nods in reply, "I just hope nothing happens for the rest of the year, it seems ever since you came to the school something happens. At least it's not during exam time this time".
Harry shrugs, "You've got a point, also, is Remus a werewolf?"
Snape's jaw drops, "What?"
"Is. Remus. A werewolf?" He says it slowly, as if he were speaking to a child, "it's not like I wouldn't notice, I follow him to the shrieking shack sometimes."
"Then why are you asking us, when you already know?" McGonagall points out, speaking primly, but looking exhausted with the events of the day, which he can't really hold against her.
"Fair enough. I guess I meant to say, "by the way, I know Remus is a werewolf", is that better?" He says.
"How many people have you told?" The Potions master still isn't scarier than Hermione, but Harry doesn't think he should tell him that right now.
"Everyone. But," he waves his arm out, "no one believed me really, so I said see if he turns up tonight, because it's a full moon, and then we'll see who's right." He taps a finger on his mouth is mock thought, "most Gryffindors probably know, so other houses do too".
"And what did they think?" McGonagall asks, a note of nervousness in her voice.
"Oh they don't particularly care, he's made a point not to eat anyone. Anyone that does has to face Hermione on a rant, so most people would rather just accept it and not make a fuss." He says the last part with pride, "She is way scarier than you, Sir."
"I see…"
"Thank you, Mr Potter". Now that's a surprise to everyone, "you may have just saved us some very tricky explaining." She starts in panic, "we haven't even told him that Sirius is innocent!"
"Because he's currently a werewolf," Harry supplies helpfully, "just tell him in the morning".
"In the morning, yes, in the morning. That's when we'll deal with the rest of this. I think it's time for bed".
"But I'm a ghost! I don't have a bedtime!" The ghost in question exclaims to Minerva.
"Yes, but I have a lot to deal with right now, Harry, maybe you can accompany Professor Snape down to the dungeons for your amusement instead."
Snape recoils, "Absolutely not. Goodnight, Minerva, Mister Potter." Amd leaves in a manner which is probably meant to make it look like he's not fleeing, when he really is.
"Goodnight!" Harry calls back, "Goodnight, Professor".
"You might as well call me Minerva," Minerva sighs out, "you are no longer a student."
"Goodnight, Minerva!" The name feels weird in his tongue, referring to his teacher by her first name years before he should have graduated. The melancholy settles over him as Minerva, stands up and leaves through a door to her quarters, "Goodnight, Harry".