"Look, it's Professor Snape 2.0!" Mingyu snickered, grinning to his other Gryffindor friends as they watched the Slytherins stroll into the Potions room. Wonwoo, the star student of Potions, and "Snape 2.0" in Mingyu's words, threw the Gryffindor a scathing glare and rolled his eyes. Mingyu always passed Potions by the skin of his teeth, mostly through his friends helping him.

The two couldn't be less alike. Wonwoo was a Pureblood Prefect, with inky black hair, pale skin and onyx eyes that made him the embodiment of a Slytherin. Mingyu was Gryffindor's star Keeper, almost never letting a goal in during Quidditch matches, and had tanned skin with dark brown hair.

Well, they had one thing in common- their mutual hatred.

If their backgrounds as a Pureblood Slytherin and a Half-Blood Gryffindor wasn't enough to justify their bad terms, one incident in Year One sure was. Mingyu and his friends had been causing a ruckus in the courtyard, distracting Wonwoo from his book of spells. And so the Slytherin hexed him to get sick, hoping he would shut up and go to the nurse's instead. He didn't expect Mingyu to get sick on HIM, puking pumpkin juice and Chocolate Frogs all over Wonwoo and his brand new robes.

And so it began, little charms or spells to ruin each other's days, never enough to get caught or punished, always enough to fuel the hatred. It was almost like they had a mutual agreement to keep it "private", for it to not affect their grades and to not let the professors take too much note of it as anything other than House rivalry.

Five years on and they were still at it. Their friends liked to compare them to James Potter and Professor Snape, with the only difference being the lack of a Lilly Evans for the two to fight over. Their O.W.L.s were approaching, and while it was looking to be a breeze for Wonwoo, Mingyu was struggling, particularly in Potions.

Potions class was ending, and Wonwoo just had his Essence of Dittany approved of, so he was looking around to see the progress of the other students. One in particular, a certain Kim Mingyu, was clearly struggling. As usual.

The tanned boy had blue smoke emitting from his cauldron, instead of the red sparks that should be coming out for him to move on to the next step. Wonwoo smirked, knowing the exact cause of the problem. The Mistletoe Berries had to be thinly sliced, and not chopped, like Mingyu had probably done.

The bell rang, and Wonwoo strolled up to the teacher's table to submit an essay for extra credit, and casually dropped in crushed Fluxweed into Mingyu's cauldron. It would be enough to make the potion seem passable, but not enough to make it effective after Mingyu had ruined it.

"Hey! What did you do to my potion!" Mingyu looked up at whoever dropped something into his potion and narrowed his eyes when he realized it was Wonwoo. The latter raised his eyebrows and said nothing, but simply turned away and walked out the classroom.

"Is there a problem Mr Kim?" 

Mingyu opened his mouth and was about to launch into a complaint about the Slytherin Prefect before the Potions Professor noted "You seem to have salvaged your potion, Mr Kim. Looks like you won't need a few additional hours in here with me to perfect it this time. You can go."

His eyes widened in shock. Mingyu couldn't remember the last time he didn't have to stay behind to re-do his potion again and again until he either had something vaguely passable, or until the professor got annoyed and let him leave. It probably wasn't