Sherlock Holmes, second year Ravenclaw, scheduled his classes so he could spend the hour after potions doing experiments. It was during one of these experiments that he accidentally invented Amortentia.
"Don’t worry, John," he said to the fifth year student who happened to be his one and only friend, "it doesn’t create actual love, just a powerful infatuation."
John had made it a habit of arriving to his own potions class an hour early so he could spend time with his friend and hear all about his latest experiments.
He’d met Sherlock on the train to Hogwarts, the first year had had his head buried in a fourth year potions book, John assumed they were in the same class and joined him in his carriage.
"Does girding potion really smell as bad as it says in the text?" The boy asked looking up from his book.
"Worse," John replied finally getting a look at the boys robes, "you haven’t even been sorted yet what are you doing with a fourth year potions book?"
"It was my brother’s, I borrowed it,” the boy replied.
"In other words he doesn’t know it’s missing," John chuckled, "I’m John."
"Sherlock," the boy said putting the book down and shaking John’s hand.
"Which house are you hoping for?" John asked making conversation.
"My brother was a Slytherin, I expect the same placement," Sherlock shrugged, "it doesn’t matter anyway. Statistically all the houses are equal academically."
"But do you want to be a Slytherin?" John asked.
"I don’t understand, why would what I want matter," Sherlock replied.
"The sorting hat takes your choice into account, if you don’t want to be Slytherin you don’t have to be," John explained.
"So if I want to be a Ravenclaw?" Sherlock posed.
"You can be a Ravenclaw, or a Hufflepuff, or even a Gryfindor like me," John smiled, "but you’re right houses don’t really matter. I know plenty of Gryfindors who are friends with people from other houses."
"I don’t have friends," Sherlock told him.
"I’m your friend," John told him.
"You don’t even know me," Sherlock protested.
"It’s a long train ride," John replied and by the time the train arrived at Hogwarts they were the best of friends.
Sherlock had been trying to make a love potion for weeks as a means of impressing a first year Slytherin named Irene. John was convinced he fancied her but Sherlock insisted that he was only interested in her because she was clever.
"It smells like parchment, tobacco ash and bow rosin," John told him.
"Odd, it smells entirely different to me," Sherlock replied.
"What do you smell?" John asked.
"Tea, the handle of a broomstick and strawberry jam," Sherlock told him.
They dragged a few students who were passing by into the classroom and had them smell the love potion, each had smelled a different combination of things.
Molly Hooper, a Hufflepuff in Sherlock’s year, smelled the sea, peonies and vanilla. A Slytherin in John’s year smelled gun powder, rain and cauldron cakes. Sherlock and John were slightly disturbed when Jim, a Slytherin in third year, said he smelled blood, tears and sulfur.
"Who did you test it on?" John asked knowing Sherlock wouldn’t have made a batch this large unless he already knew it worked.
"Phillip Anderson, the sixth year prefect from my house. He has a crush on the sixth year prefect from yours, something Donovan," Sherlock told him.
"Sally," John said with a laugh, "that explains why he followed her to quidditch practice yesterday."
"He tried to follow her into the girls lavatory too," Sherlock chuckled, "Moaning Myrtle chased him out and all the way down to the dungeons. He hid down there for an hour."
"How long did it last?" John asked.
"Almost a day," Sherlock replied, "so you’d have to keep administering it if you want to keep up the pretense for longer than that."
"Are you going to use it on Irene?" John teased as Sherlock started pouring the love potion into vials.
"No," Sherlock said derisively, "she said she’s going to use it to get people who fancy her to do her astronomy homework."
"And you believe her?" John asked, there was always something about Irene that he didn’t trust but he couldn’t put his finger on it.
"Not entirely, that’s why I’ll be diluting her potions so they’re less effective," Sherlock said hoping that John approved.
"Good idea," John told him with an approving nod.
"Want some?" Sherlock asked putting the stopper in the last bottle.
"No thanks, I’ve got enough people obsessing over me already," John said shaking his head.
"Well you are the best keeper Gryffindor’s had in decades," Sherlock replied.
"Only because I practice," John told him.
"What are you going to try next?" John asked as he helped Sherlock clean up.
"Veritaserum or Liquid Luck," Sherlock replied.
"I could definitely use some liquid luck for my O.W.L.S." John joked.
"That’s cheating, and if they find out I brewed it for you I could be expelled" Sherlock reminded him.
"I was kidding Sherlock," John said elbowing him in the ribs.
"If you’re that worried about your OWLS I’ll help you study," Sherlock suggested. "All my coursework is boring anyway and it’s the least I can do after you helped me pass my flying lessons last year."
"Hogwarts brooms aren’t the most reliable, you did fine on my Cleansweep," John reminded him.
"After six hours during which I almost fell off the darn thing two dozen times. I can’t wait until I’m old enough to apparate," Sherlock said putting the cauldron back in the cupboard.
"I’ll take the lessons next year but I’m fairly certain I’ll stick with my broom," John replied.
"Mycroft swears by apparation," Sherlock told him gathering his things and heading for the door, "he’s never been splinched, not even when he was learning."
"With my luck I’ll lose an arm and a leg on my first attempt," John called after him shaking his head.
A few days later they found out just what Irene had really wanted the love potion for when fifty points were taken from Slytherin after several students were discovered in the forbidden forest hunting for unicorns. Apparently someone had told her that unicorn blood wouldn’t curse the drinker so long as they weren’t the one to kill it.
Sherlock secretly used the left over Amortentia on all of the people who were supposedly obsessed with his best friend. He only gave them enough so that their obsession would last through the Gryfindor’s Saturday Quidditch practice and as it turned out all but a few people ended up somewhere else obsessing over people who were decidedly not John Watson.