No, my Animagus form isn't JK Rowling. She is her own lady. Unless she's a man. O.o
As Harry left the staffroom, he went over his Animagus form. It all made sense! He had no idea what that silver orb could have been, but it must have been Lupin's fear, although the only silver orb Harry could think of was the moon. When he had asked to be isolated, either he didn't have a fear or couldn't sense his own fears. He dove into his mind and was surprised. He saw the blurry outline of a box, and when he focused, he could make out the bars of the cage. That made sense too! He had hated being cooped up in the hospital wing. Maybe boggarts didn't like staying in one place too long? Harry certainly didn't, anyway.
He went back through his previous forms. Ron was terrified of spiders; that was obvious. That piece of parchment, though... That could have been Hermione's fear before she saw Harry freeze! It would be... Probably a troll-graded essay. Harry chuckled to himself at that thought. Anyway, since Hermione now feared Harry's death via freezing, it would only make sense that he would see that image twice while around her.
Maybe he saw the fear of whoever he concentrated on. That would explain boggarts' weakness; with the mind of a creature, they couldn't concentrate on only one target. Harry was more lucky, as he had the mind of a human, along with the instincts of a boggart.
His scar had probably disappeared because he had been thinking about how much he hated it. Maybe a boggart could transform into more than just people's fears, but their instincts simply wouldn't allow them?
That silver fog... The Dementors! They probably feared it, whatever it was, so he had at least partially transformed into it.
The bad reaction to the cold might have been because boggarts had that same reaction; the creatures weren't researched very well, because who would want to get close? That meant that there could be all manners of other weaknesses, strengths and secrets to them!
Harry also remembered the pain he had felt when everyone had casted Riddikulus together. He assumed that he had been caught in the magic, but it hadn't been concentrated so he hadn't been affected too badly. When they took turns casting at the boggart, all the magic was concentrated away from him. As for his own Riddikulus, he probably just hadn't noticed the pain. He hadn't noticed a cracked skull, after all.
He was brought out of his thoughts when he automatically turned to go into the gryffindor common room, and realised a moment too late that he had to open it first, planting his face into the portrait. He shook his head in a daze, then realised he didn't know the password. Glancing around, he spotted Ron and Hermione, who let him through, then he pulled them up to the boys' dorm, cast Muffliato, and turned to them.
"I think I know what my Animagus form is." And he relayed his reasonings to the pair. By the end, they were both open-mouthed, and Hermione looked like she would cry again, as Harry hadn't left out the frozen images. He probably should have thought that through, he thought, as he pulled Hermione into yet another hug.
"Mate, I think we might all be magical creatures!" Harry looked up, an eyebrow raised. "Well, you're probably a boggart, Hermione's an owl, which would use magic to sense where people are, and I think I'm a dragon. I saw mine breathe fire, anyway."
That reminded Harry. "We need to find a place to practice transforming!"
"We found a place," Hermione informed him. "There's a passage to the shrieking shack under the whomping willow, and Crookshanks stopped it from moving by pressing the knot on it."
"Well, let's go then!" He pulled the invisibility cloak out of his trunk and pulled it over their heads.
The golden trio snuck outside to the Hogwarts grounds, where Harry decided to make a detour. He ducked out of the cloak and rapped hard on the door to the wooden hut belonging to the gamekeeper of Hogwarts. After a few seconds, the door flew open and Hagrid stood there, welcoming them into his home.
"Congratulations, Professor Hagrid," Harry grinned, laying extra emphasis on the new title. "Sorry me and Hermione weren't there to clap for you."
"Ah, 'salright Harry, ah heard from them during my firs' lesson wha' happened." His beetle eyes widened slightly, and his voice became a bit more forceful. "What're you doing out here, Harry?! Sirius Black's after yeh, I'm not worth dyin' for!"
He tried to drag them back, but Harry slipped back under the cloak. "Even he can't see me under this, Hagrid. Besides, the iceboxes are keeping him out of Hogwarts. If they weren't, Dumbledore would force them out." Hagrid caved to this logic, and stopped making grabs at mid air. Harry decided to push his luck a lot. "Hagrid, do you know anything about Animagus transformations?"
The giant of a man blanched a little, and shifted uncomfortably. "Well, ah, mebbe a little," he said evasively, and Harry beamed.
"Great! So you're an Animagus." From Hagrid's shocked, fearful look, he had hit the nail on the head. "We want to be Animagi too, so we're practicing. Could you supervise us, just in case of emergency?"
Hagrid eased a little, and nodded slowly. "How far've yeh got?" He asked, seemingly uncaring that the magic was illegal, or maybe he just didn't know.
"We think we know our forms, and we've all managed to change a little," Hermione supplied, to which Hagrid carried on nodding.
"Th' place where ah practised is gone now, though," he told them. "Got anywhere else?"
"How big is your Animagus form, Hagrid?" Hermione asked him; she knew the passage wouldn't fit the big man.
"It's actually a mouse," he confessed, obviously embarrassed. "I never liked bein' in the spotligh', guess it went through to my Animagus form."
Hermione squealed in delight. "We can use the shrieking shack, after all!"
"Isn' that place haunted by ghosts, Hermione?" The shaggy man asked. "Well, I s'pose we won' know 'til we go there. Are we gonna go now?"
"Yup," the three teenagers chorused, and they led him outside and to the whomping willow.
Three chapters in one day! I really have no life .-.
Thus, the golden trio have a place to practice and a supervisor to help in doing so. It just made sense to me that Hagrid, who's crazy about creatures, would be an unregistered Animagus, and a mouse at that.
I still don't know how long I'm going to go with this, but I'm hoping to carry on past the seventh year, and into the trio's jobs or something.