To say that Y/n and Mattheo Riddle had reputations would be an understatement.

They were the two people at Hogwarts most likely to be found in a broom cupboard with someone whose name they'd forget by Tuesday. Flirtatious, shamelessly charming, allergic to commitment, and seemingly incapable of going more than a week without finding someone new to entertain themselves with. Dating was practically a competitive sport, and neither of them had ever been particularly interested in settling down.

Y/n had never been the type to get attached. The second someone showed genuine interest, the thrill was gone. Mattheo was worse — he couldn't remember anyone's birthday, rarely bothered with names, and treated relationships like a game he'd already won before it even started.

So naturally, when the two biggest players at Hogwarts somehow ended up together, everyone thought it was a disaster waiting to happen.

It started the way all great disasters do: with a party in the Slytherin common room. A game of truth or dare. A dare that ended with Mattheo kissing Y/n in front of half their year. And then another kiss after, when no one was watching. And then... a lot more kisses after that.

It was supposed to be casual. They both insisted it was casual. Just two people who understood each other, having a bit of fun. No strings, no feelings, no complications.

Except it didn't stay that way.

Somewhere between the ridiculous flirting, late-night conversations, stolen kisses and constantly finding excuses to be around each other, something changed. Mattheo, who once couldn't remember anyone's birthday, now remembers every little detail about Y/n. Y/n, who used to get bored the second someone showed genuine interest, finds themself looking forward to nothing more than spending time with him.

He's softer with Y/n. Y/n is more patient with him. They bring out a side of each other that nobody else gets to see, and neither of them has ever been happier.

Of course, neither of them is particularly interested in admitting just how serious things are getting. The L word hasn't been mentioned, and Mattheo would probably rather throw himself off the Astronomy Tower than confess how completely gone he is for Y/n. But it's becoming increasingly difficult to pretend this is just another fling.

Especially when their friends are still waiting for the inevitable disaster, completely oblivious to the fact that the two people they thought were the worst possible match have somehow become the best thing that's ever happened to each other.

Which brings us to tonight.

The Slytherin common room, late evening. The fire crackles low in the grate, casting warm shadows across the green-draped furniture. Most of the house has migrated to the Great Hall or their dormitories. A few stragglers linger by the windows, but the room has that settled, quiet feeling it only gets after a long week.

Y/n and Mattheo are curled up on one of the leather sofas, closer than strictly necessary. His arm is draped over their shoulders, absent fingers tracing slow circles against their arm. It's comfortable. Easy. The kind of quiet they've learned to exist in together.

That is, until the portrait hole swings open and the rest of the Slytherin seventh years pour in like they've been waiting for exactly the right moment to interrupt.