Disclaimer: If the Potterverse was mine, things would have gone very differently. That said, many thanks to JK Rowling for letting us play in the world she created. It's one hell of a sandbox.
Severus Snape strode into the Potions classroom, his robes billowing behind him as always. Seamus needed to figure out how he did that.
"By some unfortunate stroke of fate, you idiots have managed to qualify for NEWT-level Potions," the professor sneered. "I don't expect most of you to pass this class, as we will be brewing some of the most difficult potions known to magic. If any of you would like to do us all a favor and leave before the term can even begin, please, do so now, so that I don't waste my time with you."
None of the sixth year Gryffindors or Slytherins moved from their benches, although Neville looked as though he was ready to fly out of his seat.
Snape heaved a dramatic sigh. "Very well. There will be no time for review, so for your sake I hope you prepared over the summer holidays." Everyone except Hermione groaned.
"Now," the greasy man continued as he leaned menacingly over his desk, "Today we will start with the easiest potion of the year. This brew is simple for anyone with real talent, but as such I expect most of you will be unable to produce an Acceptable specimen. Instructions are on the board. You have one hour," he said with a flick of his wand, revealing the scribbles on the chalky surface. "NOW!" he screamed at the Gryffindors, who were moving too slowly for his taste.
Seamus and Dean quickly unpacked their kits and began their prep work. As he had for the past five years, Seamus did the cutting, measuring, and some of the ingredient adding. Dean manned the fire and the stirring, mostly to minimize the risk of Seamus blowing up yet another cauldron.
They worked together feverishly to finish within their time limit. At exactly sixty minutes, their solution had turned the exact shade of iridescent, milky white described in the textbook. From across the aisle, Seamus could see that even Harry and Hermione's didn't look quite as shimmery as their own. Bottling a sample to turn in, he placed the vial in the basket on Snape's desk as Dean put their cauldron in stasis.
The professor walked through the classroom, inspecting each cauldron with different variations of a snarl on his face. When he arrived at Dean and Seamus's desk in the back corner, Snape stopped and stared, his mouth hanging slack in spite of himself. Schooling his features, he looked both boys in the eye as if by doing so he could search their minds for signs of cheating.
"By some miracle, you two have managed to brew an Acceptable potion," the man sneered. "Though the idiots at the Wizarding Examination Authority might consider giving this an E."
Snape stalked back to his desk and began to lecture on the day's brew.
"If you bothered to do the reading, which it seems none of you did, you would know that you just brewed Zielsverwant Onthullen, which is used in detecting soulmates," he spat, as though the phrase left a bad taste in his mouth. "Tell me, can anyone explain its effects?"
Hermione raised her hand as usual, and, in keeping with tradition, Snape ignored her. "No? As expected. It was developed in 1641 by Rhodia Fleming, the only daughter of a wealthy businessman. Several suitors had already asked for her hand, and the richest one, favored by her father, claimed to be her soulmate. The simpering fool that she was, Fleming created this potion to prove her father wrong. When brewed properly, it robs the drinker of the illusion of color until he or she lays eyes on their soulmate. Of course, Fleming's father married her off to the man anyway, and she was doomed to see only in black and white for the rest of her life," Snape finished with a dismissive wave of his hand. "For homework, two feet of parchment on how the ingredients work synergistically to alter the drinker's vision, due next class."
With groans all around, the students began to pack up. Just as Dean raised his wand to vanish the potion, a hand grabbed his arm.
"Don't," Neville whispered, keeping an eye on Snape. "You should bottle that. It's worth quite a bit of gold in greenhouses and Herbology shops. Good for plant breeding," he explained. The two boys shrugged and quickly moved the contents into several vials, which they stuffed in their bags and hauled back to Gryffindor Tower.
Seamus and Dean found themselves alone in their dorm room. Neville had gone straight to the greenhouses after Potions, and Harry and Ron were off plotting Merlin-knew-what with Hermione in the library.
Seamus pulled out a couple vials and waggled them at Dean. "Wanna give it a go, mate?"
"Are you crazy?!" Dean cried, his eyebrows shooting into his hairline. "I'm not so desperate to find my soulmate that I'd drink some shit we brewed in Snape's class. Besides, he said it wasn't even that good. Probably won't even work."
"Then all the more reason to try it! Or are you too scared?" Seamus taunted. He held his breath, not sure which answer he really wanted from his best friend. On the one hand, this could confirm once and for all what he felt to be true- that he and Dean were meant to be together. On the other, it could prove him wrong and crush Seamus's heart. But either way, the Gryffindor wanted the truth.
"Fine!" Dean shot back. He snatched a flask out of his roommate's hands. "But I'm not taking my eyes off you- I don't trust you not to fake it, you cheeky prat," he teased. With a deep breath, he murmured, "On the count of three- one."
"Two," Seamus crescendoed.
"Three!" they shouted in unison.
Never blinking or breaking eye contact, the two boys each swallowed a generous mouthful. Not bad, Seamus thought, kind of like maple syrup.
They waited for the potion to take effect. And waited. And waited. And waited.
"I don't think it worked, mate," Dean observed. "Nothing looks any different."
Seamus deflated a bit, sad that he didn't get his answer. "Yeah, looks like it's a dud. Oh well, at least-"
Harry and Ron can barreling through the door, laughing loudly at something. They stopped short when they saw the vials in Seamus and Dean's hands.
"Eh, how'd it go there, Seamus?" Ron asked. "How's life in black and white."
Seamus snorted. "Couldn't tell ya, it didn't work."
Harry cocked his head to the side. "Really? Hermione seemed to think it was a perfect brew."
"You wanna try it?" Dean asked jokingly.
"Sure," Harry replied, shocking them all. "What?" he asked sheepishly, "I'm going to see Ginny in a few minutes anyway. I'll be fixed right up."
"Dude, shut up, that's my sister!" Ron interjected.
"So sure there, Potter," Dean laughed, passing him the vial. "Have a swig."
Harry shook himself and then took a large gulp of the milky liquid.
"Merlin, that was fast!" he exclaimed, removing his glasses to rub his eyes. "I didn't even swallow before everything went black and white. Damn!" He glanced at Ron. "Oi, you look a sight better this way!" he joked.
The two-thirds of the Golden Trio began exchanging playful jabs as Seamus and Dean surreptitiously locked eyes. Why hadn't it worked for them?
"Come on now, let's go get this under control," Ron urged. "We can't have you playing Quidditch with the eyesight of Labrador."
The four roommates trooped down the stairs in search of Ginny Weasley. Harry stood at the foot of the girls' stairs, ready to call out for the redhead when Hermione came barreling down the staircase into Harry's chest.
"Oomph- Harry, what are you doing standing there?" she asked with a confused pout.
All Harry could do was stare at his female best friend. "Ho. Lee. Shit."
Ron's face reddened as the famous Weasley temper flared. "Do you mean to tell me-"
"Mate, you know I couldn't help it!" Harry cried.
"Couldn't help what?!" Hermione cried, frustrated at being left out of the loop.
Sensing an impending blow up between the members of the Golden Trio, Dean and Seamus slowly backed away and fled to their dorm room.
"Oh-kayyyyyy, it does work," Seamus surmised.
Dean nodded and then grew pensive. "If it worked for Harry, why not us?"
Seamus shrugged. "It's not toxic. We could try it again?"
"Let's stand back to back and act normal this time," Dean suggested. "Maybe we screwed up by staring at someone while we drank it."
Standing between their beds, the two best friends each took another large swallow of the rather tasty potion. Seamus was amazed at how quickly the color leached from the bed hangings and rugs in the room.
"Woah!" they cried in concert.
Turning back around, they locked eyes and stood in silent shock as color flooded their world again.
"Ho. Lee. Shit." Seamus whispered.
"Does this mean-" Dean breathed.
Seamus simply nodded.
"Thank Merlin," Dean murmured, taking Seamus's face in his hands and crashing a kiss onto his lips.
AN: for therevolutionsayshi and the HPFC monthly one-shot exchange- your prompts were challenging but fun to work with. I hope you like it!