They had been neck-to-neck in almost every aspect of their lives for as long as either of them could remember. They came from a long legacy of rivals (all right, not that long; their fathers had been enemies over something neither of them could recall, but they were sure it was important), and and thus this, of course, meant a bitter feud between Flynns and Dillingers until the end of time.
It wasn't that difficult, really. Sam thought Edward was a pompous, arrogant, self-entitled son-of-a-bitch, and Edward considered the young Flynn a lazy, callous, clown whose every achievement was a pure stroke of luck. The fact that they were in opposing rival houses probably didn't help much either.
This had been their impressions of eachother since they had been paired up in potions the first day of their first year and melted a cauldron (among other things); Ed had insisted the Runespoor egg went before the Salamander Blood and Sam being Sam had insisted otherwise and, well…Many points had been lost that day. For both houses.
When Sam had been chosen Chaser for the Gryffindor team in his third year, no one had been too surprised when Ed had showed up as Keeper for the Slytherin team at the next match. When they both wound up in the infirmary, Sam with a bloody nose from a bludger to the face (Ed claimed the Gryffindor's face had simply gotten in the bludger's way), and Ed with a broken rib from an accidental, sudden veering of Sam's broom, no one was particularly surprised.
Everyone quickly learned it was better to keep the two as far apart as possible.
As the years went by, the "accidents" went down in number, the boys preferring verbal and psychological taunts in place of physical abuse. Nonetheless, teachers and students made a point of not pairing them together for anything if they wanted to avoid casualties. Even their parents made an effort to pick them up in separate areas of Platform 9 3/4- It had nothing to do with their own old rivalry (in their older age, both parties had better things to concern themselves with), they simply didn't want their sons coming within ten feet of each other and sending parents with younger children fleeing from the litany of curses both were sure to expel.
Around their 7th year, the physical abuse returned with a vengeance- and a twist.
Neither could remember when their impromptu angry, hate-sex sessions had begun, perhaps it had been after a particularly heated Quidditch match, or maybe Ed had been angry when Sam had pulled ahead of him on their midterms by two points. All they knew is that one moment they were hurling swears at eachother, wands at the ready in an empty class room, and the next moment Sam found himself locked against the wall by strong, remarkably toned arms as the Slytherin's lips and teeth felt their way to the sensitive skin of Sam's neck, making him gasp in surprise mingled with pleasure.
Ed's wand had rolled away several feet and lay forgotten on the floor, Sam's following shortly once he'd made quick work of the door lock.
Everything was hands gliding over hard muscle and scratches that made the brunette hiss as his hips ground forcefully against Sam's, the groan the Gryffindor uttered in response only encouraging him further as he nipped sharply at the blonde's collarbone. Ed's hands slid down to hastily shove the fabric of Sam's jeans down his hips, vaguely surprised to find his own already around his ankles and wondering when, exactly, Sam had pulled that one off without his noticing.
That mystery was pushed to the back of his mind as the next several moments were filled by grudgingly muffled groans of encouragement and pleasure, Sam's legs wound tightly around Ed's torso as the Slytherin's fingers gripped his ass tight enough to leave bruises the blond's girlfriend would be sure to question later.
Ed was still blinking white stars out of his vision ten minutes later as Sam gingerly got to his feet, wincing slightly and shooting his rival a glare at the breathless snicker he received in response.
When they left that empty classroom looking disheveled and rather worse for the wear, shirts half-buttoned and glasses skewed, no one was particularly surprised; there were bets going on how long before the Flynn boy socked Dillinger in his pretty face.
The 8th day Ed walked in with a bloody lip and Sam with nail-shaped crescent moons on his arms, the professors raised a concerned eyebrow, but chalked it up to boys being boys.
The occasional sharp-eyed student, however, could hardly miss the faint, self-satisfied smirk that appeared on the Slytherin's lips every time his gaze landed on his blonde rival or the way Sam would "zone out" while conveniently staring at what a 6th year had accusingly claimed was Ed's ass.
The angry red scratches etched into Sam's back went largely unnoticed once the Gryffindor student broke up with his (somewhat un-broken-hearted girlfriend.
And when roughly a year later, after graduation from Hogwarts, Sam and Ed rented an apartment and moved in together, well…
No one was particularly surprised.