If asked, Hermione wouldn't have expected Slytherin to know how to dance – he'd been born and raised in a time 500 years before the waltz, for Merlin's sake. But he does – he moves like a snake, his moves fluid and liquid as they dance together to the beat. He rolls his head, and the move travels down his arms and his chest, rolling into his hips and legs and feet, like one big wave. Hermione idly wonders where he learned how to dance as she moves her hips, dancing.