A/N: I've switched up several things for the sake of the story, 1) Double potions class is Slytherin-Hufflepuff and Gryffindor-Ravenclaw. And, I really don't know about the military academies mentioned here. I just looked up military academies in America and stuck 'em in. Also, I know they mentioned 'The Draught of Living Death' in the first year, but I highly doubt they actually created it until Slughorn showed up. So, I've given the students a week to work on the specifics of the potion in the story. Also, special shout out to TheAmazingAnita! Thank you for reviewing- this one is for you! Disclaimer: I don't own Sherlock or Harry Potter. The British own them.

Snape growled his usual, "Turn to page three hundred and ninety-four. " Sherlock did so, and studied the potion, 'the Draught of Living Death' closely.

Sherlock had developed quite a reputation in his first week at Hogworts. Everyone studiously avoided him like the plague. It pleased Sherlock and he continued to work alone.

Sherlock held back a groan as they reviewed the information, he knew all of this already. Finally though, review was over and he took out his asphodel root and infusion of wormwood. Professor Snape was finally letting them create their first potion.

A boy rushed in the classroom with his bags banging on his hip. Sherlock glanced up surreptitiously from his cauldron where he was slowly and meticulously grinding his asphodel root into powder. He had already added the infusion of wormwood.

The boy spotted Sherlock's otherwise empty table and hurried quietly over to it, keeping his head down.

Snape glanced up and said, "John Watson, you're late. Five points from Gryffindor."

A few Gryiffandors scowled but a well-rounded boy (Mike Stamford?) waved to Watson and Watson smiled wearily back.

The blond boy gently placed a things next to Sherlock's before he pulled out his cauldron. Sherlock held out his hand and asked, "May I borrow your potions book?"

Watson looked up, "What?"

"Your potions book. I need to check something." Watson handed it over warily.

Sherlock flipped through it and then handed it back before asking, "Massanutten or Missouri?"

"E- excuse me?"

"You were sent to a military camp in America. Was it the Missouri Military Academy or the Massanutten Military Academy?"

"M- Missouri."

Sherlock smirked as he added his root to the bubbling liquid. He loved being right.

Watson prepared his infusion of wormwood and added it before speaking again.

"How did you do that?"

"I know that you went to a military academy in America, I that you're an orphan who's father used to be in the military. I also know he was abusive after he returned from the war, and that your mother died of cancer. I know that you wanted to be in the military before you discovered your magic and you desire to be an Auror now that you have magic. I also know that you have psychosomatic limp, from a weapons accident. I know that you've got a brother you had to leave behind in the orphanage, I assume you have been in contact with him."

"Holmes! Watson! Stop that chattering or you'll get detention! Another five points from Gryffindor and five points from Ravenclaw."

Sherlock added his root to the slightly lavender colored potion.

Watson started cutting his own root and methodically added it to his cauldron, before whispering, "How on Ear- How in Merlin's beard did you do that?"

Sherlock only smirked as he stirred his potion twice clockwise and added his sloth brain.

One or two hours later.

Sherlock poured a tar black potion into his flask before he stepped forward to Snape's desk and handed it to the greasy-haired professor.

Snape raised his eyebrows in, and if Sherlock had been less of a genius- he wouldn't have been able to detect it, an emotion called surprise.

"Holmes."

"Sir." Growled Sherlock before he stalked back to his desk. Watson had, surprisingly enough, a decent potion. Sherlock estimated, if it had been a test, an A or a P. Perhaps an O if Snape was feeling generous.

As the students flooded the corridor, Sherlock was surprised to see Watson chase after him and ask, "How did you do that... Thing, by the way?"

Sherlock grinned, he did love showing off.

"You've got a trace of American twang to your speech- that indicates some time in America, also, you've a tan on your hands that stops at your wrists. Obviously, you've been somewhere sunny, but you haven't been sunbathing. Abroad in America, in the summer. But, why a military academy? You are more muscular then most teens of your age and you walk with a slight limp- because there was an accident with weapons. Why it was weapons, there are several points I won't go into. It must've been military. I know you had an abusive father since you flinch away from almost anybody near you and have been acclimatized to loud noises such as yelling. Your mother... Well, you're an orphan obviously by the way everything is second hand and in the station, no one came to see you off. I know you desire to be an Auror because of notes in your book... Notes on potions and Defense against the Dark Arts and about how they're important to the future. I also know about your brother because in the front of your potions book it said 'With love from Harry.' I know you don't want to take after your father in the military- more because you want to protect other people- sentiment gets in the way. Of course, the two least expensive military academies in America are Massanutten and Missouri."

Watson shook his head. "Wow. That is... Amazing."

Sherlock jerked his head sideways. "What?"

"It was amazing- brilliant."

"Really? That's not what people usually say."

"What do they usually say?"

"Piss off."

Watson grinned and Sherlock gave one of his own back before asking, "I can't believe I got it all right, I usually miss at least one thing."

"Well... Harry's my sister."

Sherlock groaned, "There's always something!"

Watson just grinned as they made their way to transfiguration.