Everyone knew the Riddle brothers—Tom and Mattheo—were untouchable. Feared. Respected. Their presence turned heads and quieted rooms. They moved through Hogwarts like kings in waiting, their names leaving a mark no one dared challenge.

So when {{user}}, their younger sister, transferred in a year below to fifth year, it stirred curiosity, confusion, even disbelief. A Riddle in Hufflepuff? Sweet, polite, always smiling? It went against everything people thought they knew about the family name.

But she didn’t carry herself like a Riddle. Not like them. She was all warmth where her brothers were winter steel.

And that made her dangerous in a different way.

No one said a word.
Not because they weren’t curious.
But because one glare from Tom could freeze time. And Mattheo’s reputation for fist fights? It did the rest. She was off-limits. Completely and silently protected.

The afternoon had arrived. Hogwarts was calm—no classes, no schedules. The Slytherin boys had taken to the backyard, a quiet escape. Tom sat on a stone bench, eyes lost in thought. Draco lay sprawled on the grass. Blaise tossed pebbles into the pond, Regulus leaned against a wall, and Lorenzo sketched in his book.

Theo, however, stood apart from the rest, eyes fixed on the door. He’d been waiting for a while, but no one spoke of it. They knew who he was watching for.

Then the door opened.

Mattheo appeared first, pulling {{user}} gently from the castle. She followed, relaxed despite just waking up. Mattheo’s gaze flicked to the group as they walked toward them.

{{user}} was quiet, still soft from sleep, her presence filling the space. It wasn’t remarkable, but to the Slytherins, it shifted something. She was always around, but she made everything feel just a little different.

Mattheo walked beside her, making sure she was part of it all. To the others, it was no surprise. She had a place among them, effortlessly fitting in.

As they reached the group, Mattheo nodded to Theo and the others, dropping his sister off without a word. His gaze lingered on her just a second too long before he pulled back.

Theo, standing a few feet away, felt the shift. The moment Mattheo left her with them, something changed. His heart skipped, an unexpected pull he hadn’t prepared for. She was Mattheo’s sister—off-limits, no matter how easy she was to be around. She didn’t belong in their world, but she fit into it anyway.

Mattheo had warned him without saying a word. She was his sister. Untouchable.

But even knowing that didn’t stop Theo from noticing how the world seemed brighter with her there, how everything felt a little more peaceful when she smiled or laughed.

For a moment, Theo found himself wondering if she had any idea how different she made everything feel.

She was sunshine in Slytherin shadows.
And she had no idea.

Tom and Mattheo had seen it, of course—the way Theo looked at her. The way her presence bent something in him, softened the edges. The brothers were older. Sharper. Wiser. They’d seen chemistry like this before.

They didn’t speak of it, but they knew. And though they were unbothered on the surface, their silence wasn’t without weight.

They were watching. Quiet. Aware.
Not angry.
Just cautious. They knew Theo would never hurt their little sister, because if he did… he’d have to deal with the both of them.