The three new professors boarded the train rather quickly as the students were encumbered with luggage and such whereas they only had the one small bag that Lupin was carrying. The haggard young man led the way to an unoccupied cabin and took a seat, gesturing for Sam and Dean to take the other. "So this is your first time to Hogwarts then?" Lupin asked pleasantly, smiling at the two as he settled back into his seat.
"Uh, yeah, that's right." Sam nodded. He paused and then quickly added, "But I'm sure that it's a great place."
"The best wizarding school in the world." Lupin said confidently, his smile growing slightly. He paused meaningfully, almost as though waiting for Sam and Dean to argue the point and then raised an eyebrow. "Odd, I had thought you would say something against that effect."
"Yeah, well, haven't been there so who are we to judge?" Dean said honestly. He glanced to the glass in the doors as students in black robes began to pass by. "So, if you don't mind my asking, how do you deal with the whole… werewolf thing?"
"You know, it still fascinates me that you haven't once looked at me different even knowing that I am a werewolf." Lupin said amusedly. The amusement lasted only a few moments before his face became more drawn and he sighed. "To make a long story short, have you ever heard of a werewolf by the name of Fenrir Greyback?"
"A werewolf determined to overthrow the current government for their persecution of werewolves with ties to Dark Wizards." Sam nodded, assuming his role as an Auror would have given him access to such information. "Yeah, we've been keeping tabs on him."
"Well my father offended him in some way and you see the results." Lupin smiled quietly. "You know, my parents were worried that my affliction would prevent me from ever attending Hogwarts, let alone any formal schooling. Thankfully enough Professor Dumbledore did not bat an eye even after being told."
"Sounds like a great guy." Dean said.
"He is, that and more." Lupin agreed. He yawned, covering his mouth with one hand and leaned his head against the window. "If you two don't mind, I would like to get some sleep. Changes leave me very tired for several days."
"Yeah, sure." Sam nodded, rising from his seat a bit too quickly. "Dean, can I talk to you for a sec?"
Dean followed his brother out of the cabin, closing the door quietly after them in consideration for his new sleeping friend. Sam moved down the train a few cabins and opened one that was relatively empty, ushering the kids out of the cabin with the reason 'professor business' and closed the door behind him. "What's your deal?" The elder brother asked curiously, seeing the tension on his brother's face.
"Look, I don't know how the Guide brought us here or anything like that, but I do know we can't affect the timeline." Sam said urgently, gripping his brother's shoulders.
"Affect the timeline?" Dean said, shrugging Sam's hands off of him. "What do you mean?"
"In the books, Harry never tripped over luggage." Sam explained quickly. "And the books definitely never had us."
"You know, I wondered how long it would take you two to come across that little dilemma." The Guide's familiar voice, filled with concealed laughter, echoed through the cabin. A few moments later she materialized on the seat beside the Winchesters, garbed in the same black robes that the Winchesters were wearing. She smiled pleasantly at the Winchesters as she crossed her legs and put her hands behind her head. "Nice seeing you two again, enjoying the wizarding world?"
"Are you just going to drop by whenever you want?" Dean asked coldly, poking his head into the aisle and seeing that the Guide had not frozen time for this appearance.
"I could." She said fairly, pursing her lips and tilting her head to one side. "But no, I don't think so. I just thought I would pop in and let you know that Sam is right, you affect the timeline. Well, the one that he knows at any rate. But time and circumstance are subject to constant temporal flux. You can't truly be here without affecting something."
"So everything that I know about this universe is useless?" Sam demanded, making a sound of annoyance in his throat. "Great."
"Oh, I wouldn't say useless." Guide corrected. "You might affect some things, some big and some large, but for the most part the central destiny of this universe won't change. Not unless you two really screw up. So try not to do that, eh?"
Dean opened his mouth to ask a question but, at that moment, a student threw open the cabin door and nearly knocked the professor over as he leapt inside the cabin. Sam caught the staggering Dean and helped him regain his balance, noting that the Guide had vanished. "What's going on?" Sam demanded once Dean had turned around to face the student. "We were having a conversation, did you want to get-."
"Th- they're here!" the student, a small mousy haired blonde boy, said with terror evident in his voice. "D-d-d-."
Dean pulled the student deeper into the cabin and reached behind his back, presumably to where he always kept his gun, and came up with nothing. "No guns here." Sam reminded him, drawing his wand. He knew what the young boy, whom he vaguely remembered as Colin something-or-other, had seen. Sure enough, a few moments later a cold feeling of dread swept through the cabin. To the Winchesters, who had been through hell, purgatory, and watching the death of countess friends, the effects of the dementors were terrible. But they had survived all of those experiences, those and more, and misery was a feeling that they were more than used to.
"You want some?" Dean demanded, his face pale but determined. He drew his wand and leveled it at the dark-robed figure. "Bring it on, bitch!"
The dementor seemed to sense Dean's hostility and extended one emaciated hand towards the Winchester, who stood his ground defiantly. Though he had read about it, Sam had truly underestimated how difficult it was to conjure up feelings of happiness in the face of such hopelessness. His body felt heavy but seeing Dean in danger, as it always did, gave him a surge of energy. He dredged up the memory of seeing Dean after he had returned from death the first time and shouted, "Expecto Patronum!" For a long heartbeat it seemed as though the spell would fail, but a figure suddenly burst forth from the tip of his wand.
The silver figure, a long serpent, slithered through the air and wrapped itself around the dementor, staggering the foul creature. The dementor made an inhuman shrieking sound and fled the cabin, the door sliding shut behind it. The effects of the dementor disappeared once the door was closed and the young student collapsed onto a seat and started to weep into his hands. "Hey, come on." Dean said, giving his shoulder a small shake. "Toughen up, crying doesn't do you any good."
"Looks like beginner's luck is a thing here." Sam said offhandedly, staring down at the serpent as it coiled up on the floor.
"The hell is that thing?" Dean asked curiously, crouching down to examine the snake. He outstretched his hand to touch it and the Patronus snapped at his hands, causing him to quickly retract it.
"It's called a Patronus Charm." Sam explained. "They ward off dementors, that thing you just saw. You just say the words I did and think of the happiest memory you can."
Screams echoed throughout the train then, presumably as dementors considered their raid of the train. "Does it kill them?" Dean asked brusquely, thinking on his happiest memory.
"No, just gets rid of them." Sam said. "But that's good enough for now. Remus should be waking up any second now."
"Let's do this." Dean said, opening the cabin door and stepping into the aisle with his wand drawn. Sam followed a moment later, watching each side as Dean closed the door. He paused before it was totally shut and poked his head back inside the cabin. "Hey, I meant it. Quit crying. It never did anyone any good." He told Colin sternly.
Once the door to the cabin was closed Sam and Dean glanced at one another and nodded. Sam went off in one direction whilst Dean took the other. Sam's serpent slithered a few meters in front of him, acting as a deterrent between him and the dementors.
"Happiest memory…" Dean murmured, still thinking about that. He had by no means had an easy life, but he had some happy times. The problem for Dean was that for every happy memory he had, there was usually a sad one accompanying it. His first idea had been when Sam had returned from the Cage, but then came the memory that he had temporarily lost his soul there. He thought of when he lost the Mark of Cain, but that too was marred. He had tried to kill Sam mere moments before. "Come on, happy memory!" He snarled to himself.
A moment later, screams rang out a few cabins before him. For whatever reason, this had a jumpstarting effect on his memory. The one that swam to his mind was a simple one, nothing truly spectacular about it. But it was happy, truly happy. He, Sam, and Cas had just returned from a hunt and were sitting around a table. This was when Cas had lost his grace and was human, still getting used to the ins and outs of humanity. They had been gathered around the bunker's table and were just drinking and talking. It wasn't anything special, most wouldn't even consider it, but to Dean it was important. Laughing, drinking, and simply talking about nothing with the two most important people in his life.
The dementor who was terrorizing the students paused as it sensed the good thoughts flowing through Dean. Raising his wand, Dean repeated the words that Sam had only a few minutes before. "Expecto Patronum!" From the tip of his wand burst forth a large silver creature, bounding forward on four legs to charge the dementor and send it screeching away. The patronus watched the dark figure retreat and then trotted lightly back to its caster, staring at Dean. "Badass." Dean said, reaching out to touch the patronus. The silver impala reared back slightly and then disappeared in a fine silver mist.