This is a concept I had out there for a while. It's a Grimm/Sherlock/HP crossover, so that's what that is. Any questions, leave them in the comments.

Chapter 1- The Hogwarts Express

John Watson looked in awe at the gleaming black-and-red train that lay in the station before him. Smoke puffed lightly out of its stack as the students boarded to be on their way to Hogwarts.

John still wasn't entirely convinced that this whole business of a wizard school wasn't some sort of elaborate joke. However, he had the robes, cauldron, books, wand, and even a bloody owl, so he figured there must be something to it.

Watson looked up at his father, uncertain of what to say to the man. His father had never been anything that could be called involved in John's life. "Er… Dad, I-"

"Go on, John," his father said, "or you'll miss our train."

John nodded, gathered his things, and climbed aboard the Hogwarts Express, walking along the crowded corridors until he found a compartment with only one person in it.

The occupant was a tall, thin boy with curly black hair and a long dark coat wrapped around him tightly. His eyes were closed, but they opened when John entered the compartment, and the boy looked him over critically before speaking.

"Military or police?"

"Er… sorry, what?"

"Your father. Is he military or police?"

"Uh, military, how did you-"

When the boy began speaking, John found himself interrupted for the second time in 15 seconds. "You have the disappointed look all over your face that suggests you were looking from some sort of emotional affirmation today, but you didn't receive it. The most likely source of emotional affirmation for an 11-year-old is a parent, so at least one of yours is at least emotionally, if not physically, absent. The father is statistically more likely, and there are any number of reasons why he may not pay you the attention you were hoping for, but I noticed your bearing and your haircut. Even under the proverbial weight of your disappointment, you stand perfectly straight, shoulders squared, et cetera. 'But wait, what's my haircut got to do with it?' Please, it's practically shaved off, it's obvious. So, you've an emotionally absent father whose only lessons to you have been about discipline and self-control, so he's a member of some organization whose code is devoted to those values, thus- military or police, as you've just answered." He looked evenly at John. "Simple, really."

"That was simple?" John asked in disbelief.

"Obviously."

"Now now, Sherlock, don't show off," a girl's voice said from behind Watson. He turned and saw a blonde girl standing in the doorway, smiling slightly.

The black-haired boy, Sherlock, snorted. "Of course I'm going to show off, Adalind, it's what I do."

John moved aside to let the girl in, and she stowed her luggage in the rack over the seats, then sat down. John followed suit, taking the seat next to Sherlock and across the compartment from the girl named Adalind, who smiled at him.

"I'm Adalind Schade, and that's Sherlock Holmes," she said.

"Oh, I'm John Watson." He looked around. "I still can't believe all this stuff about magic and wizard schools is true."

"Believe it," Sherlock said. "Once you eliminate the impossible, whatever remains, however improbable, must be true."

Adalind rolled her eyes as the door opened again and a pale, sharp-featured boy entered the compartment.

"John," Adalind said, cutting off any further from Sherlock, "this is Scorpius Malfoy. Scorpius, this is John Watson."

Scorpius nodded briefly to John and sat next to Adalind. "Where're you from?" he asked as he sat.

John figured the question was directed at him, so he said, "Northumberland. So, you three all know each other?"

"Hardly a difficult observation, but yes," Sherlock said. "Our parents- Adalind's mother, Scorpius' and my fathers- work for the Ministry, so we met through them." He closed his eyes and steepled his fingers.

"There's also a girl named Gwen Wright, who's probably on the train somewhere," Adalind said. "Wherever she is, she's probably getting into some sort of trouble."

O.O.O.O

The girl was staring at him.

Éamon O'Driscoll's flat cap was pulled down over his eyes, and he was pretending to be asleep, but he could tell somehow that the girl who was sitting across the compartment from him was staring at him.

He shifted in his seat, trying to get her to stop without actually communicating with her. It didn't work, however, and he was forced to sit up and confront her, which was annoying.

"D'ye want somethin'?" he demanded, pushing his hat back and centering it on his head.

The girl had an expression of curiosity on her face as she looked at him. Her hair was brown and braided with a length of ribbon, and her eyes were a swampy green. When Éamon spoke, she shook her head.

"Nah," she said, "ye just look familiar. D'Ah know ye?"

"Ye been ta West Cahrk?"

She shook her head, and Éamon said, "Then we've ne'er met."

The girl smiled like an idiot. "Ah'm Nicole Buchanan."

"Éamon O'Driscoll." He nodded curtly and pulled his hat back down over his eyes as the train pulled out of the station.

After a moment, the door opened again, and a girl's voice with an upper-class English accent asked, "Can I join you two?"

"Aye, 'course," Buchanan said. "I'm Nicole Buchanan, an' this's Éamon O'Driscoll. He ain't much fer conversation, though."

"Gwen Wright," the new girl said as she sat next to Éamon. "So, what're your hopes when it comes to Houses?"

"Well, Da was in Hufflepuff, an' Mam was a Muggle," Nicole said, "but Ah donnae hae any preference." Éamon could tell she was looking at him again. "Whit aboat ye?"

O'Driscoll didn't respond, and without warning, his hat was snatched off his head. He glared across the compartment at Buchanan who was holding it and smiling like an idiot. Again.

"Gimme me goddam hat back," he snapped.

She shook her head and put his hat on herself. "Answer m'questions."

"Why the fuck should Oi do tha'?"

"Tsk, language. 'Cause Ah've got yer hat, an' if ye donnae talk, Ah'll set on it."

Éamon growled, but said, "Mam was in Slytherin, Da an' m'aulder brother got put in Ravenclaw. Now gimme me goddam hat back."

"Ah donnae think so."

"It wasn' a goddam request," he growled.

She smirked. "If ye want't back, ye should be nicer tae me." With that, she took his cap and sat on it. Éamon growled angrily and launched himself at her, but she rolled to the side and grabbed him in a tight hug.

"Awww, yer such a sweetheart," she giggled. Éamon pulled away, snatched his hat out from under her, and sat back down, pulling his hat back down over his eyes.

"Lemme alone, ye damn crazy Scotswoman," he snapped. "An' if ye touch me hat again, Oi'll break yer goddam fingers."

"That seems excessive," the English girl, Gwen Wright, said mildly.

Éamon spoke without looking at her. "It became yer business when, Sasanach?"

"Well, you're a regular ray of sunshine, aren't you?"

"Go roide a kelpie."

The door opened again, and Éamon heard the most wonderful sound in the world- the voice of a fellow Corkman.

"Kin Oi join ye? The whole bloody train's full."

O'Driscoll pushed his cap back and saw a short boy with dark eyes standing in the doorway, shifting his weight from foot to foot.

"Aye, c'mon in," Buchanan said cheerfully.

The boy sat down across from Éamon, who looked at him warily. "'S yer clan?"

"Moriarty. Jim Moriarty," the boy said. "You?"

"Éamon O'Driscoll. Makes y'an ally, aye?" He offered a hand, which Moriarty took.

"Guess it does, aye."

Gwen Wright rolled her eyes to Heaven. "This'll be lovely, won't it?"

O.O.O.O

There were five people squeezed into the compartment where Eddie Monroe sat as the Hogwarts Express rolled on through the Scottish Highlands. There were, apart from Monroe himself, two dark-haired boys named Nick Burkhardt and Sean Renard, a black boy named Hank Griffin, and a Chinese boy named Reggie Wu.

Monroe felt very nervous around so many people, given how close a proximity he was in to them, and how long he had been that close. His woge had started a few months before his Hogwarts letter had arrived, and he was still learning to control it properly.

"So," Hank said, "how exactly do these Houses you mentioned work?" He and Wu were Muggle-born, and still unclear on the workings of Hogwarts.

Sean steepled his fingers. "The way my brother Eric described it, you put on the Sorting Hat, and it looks into your mind somehow, and determines your House based on your dominant personality traits- Gryffindor for courage, Hufflepuff for industry, Ravenclaw for intelligence, or Slytherin for cunning. The Houses get points for successes, or lose them for breaking rules, and at the end of the year, the House with the most points wins the House Cup."

"Which House is your brother in?" Monore asked.

"Slytherin. Whole family's in Slytherin." He fell silent for a moment, faced closed down and brooding, before he said, "What about you and… Nick, right?"

Nick nodded. "Dad was in Ravenclaw, and Mom was a Muggle."

"My mom was in Hufflepuff, and dad's whole family were Muggles."

Sean nodded and looked out the window. "We're almost there, I think we should change into our robes."

They did as he suggested, and soon the train pulled into Hogsmeade station, where the first years were led to boats which took them across the lake.

As the castle loomed out of the fog, Monroe looked up at the massive structure. "My God…"