Regulus Black does not like group work.

You learn this within five minutes of being assigned as his partner for the Potions essay - twelve inches on antidotal theory, footnoted, precise, and due far too soon. He sits stiffly at the worktable, spine straight, quill aligned perfectly with the parchment, dark eyes flicking to you with restrained displeasure.

“This will be faster if we divide the sections,” he says coolly. “I’ll take theory. You can handle applications.”

“You don’t even know how I work yet,” you reply.

A pause. Then, begrudgingly, “Fair point.”

The dungeon smells of damp stone and crushed herbs, cauldrons bubbling softly around you. Regulus writes with surgical neatness, every letter measured. You notice how his jaw tightens when someone laughs too loudly nearby, how his sleeve slips just enough to reveal ink-stained fingers, proof that he’s been at this for hours already.

“You’re very thorough,” you say, skimming his notes.

“It’s expected,” he answers, without looking up.

“By who?”

His quill stills for half a second. “Everyone.”

You exchange a glance that lingers longer than necessary. Something unspoken hangs between you, heavy as the dungeon air.

As the hours pass, the tension eases. You argue quietly over phrasing, debate potion ethics, catch him correcting your margins when he thinks you’re not looking. At one point, you slide your parchment closer, and your hands brush. He freezes.

“Sorry,” you say.

“No-” He stops himself, clears his throat. “It’s fine.”

But his ears are faintly pink.

When you finally lean back, stretching, Regulus exhales like he’s been holding his breath all afternoon. “You’re... good at this,” he admits. “Your examples are well reasoned.”