Since he was young, Sirius hated the dance lessons his mother would force him into with Regulus. Not being able to do anything about it as it was part of being a proper Black, he would drag himself through it, purposely dancing with two left feet even if he was actually good at it just to spite at his mother. He stopped doing it when the dance instructor would discipline him with a thin stick that gave him bruises. Besides, showing his proficiency would mean the lessons would stop. It was the only upside of it.
Living with the Potters meant no Black family events where he was required to dance with a proper lady or a purebred cousin; meaning it was also a way to introduce him to marriage prospects. Dancing was one of the things Sirius hated the most since it reminded him so much of the ways of the family who disowned him.
Unfortunately, he couldn't escape it when Hogwarts held a Yule Ball. He was tempted not to go but with Marlene eying him hopefully, and James, Peter, and Remus were also coming with their respective dates, Sirius gave in.
The same evening he agreed, Remus admitted offhandedly that he pitied his partner—a Ravenclaw a year below them—because he has two left feet and never danced before.
Sirius, without thinking it through, offered to teach Remus. Remus was touched by the offer but warned him that he would be stepping on Sirius feet a lot of times before they could get through the basics.
Sirius thought it was still more fun than a thin wooden stick.
Three evenings before the ball, they were practicing for at least an hour or so. For somebody who hated dancing so much, Sirius was patient to teach Remus step per step, laughing when his toes got stepped on and encourages Remus further. Most of the time, Sirius would take the female role, but he secretly liked it when the roles were reversed since he was much closer to Moony that way and could feel his waist under his palms. Sirius was a few inches taller than Remus that time and he liked it when the latter would look up to him with grateful, bright eyes. It wasn't even full moon but the sky was clear and Sirius could see a thin stripe of moonlight hitting Moony's head, making his hair shine ethereally as the few wisps tickling Sirius' cheek.
Suddenly, Sirius realized that he was in-love with this wonderful person who was awkward and a bookworm with a penchant for chocolates that he practically smelled like one. Holding Remus' hand with his left hand and the other on Remus' waist, Sirius was thinking that it was so easy to close the intimate distance between them.
He didn't, and in the end, Sirius was left with a raging heartbeat.
During the Yule Ball, Sirius' eyes would dart towards Remus and his partner who were slow dancing not far from James and Lily. There was a well hidden jealousy in him and thought that it should have been him in place of Remus' partner.
Marlene excusing herself went past Sirius, which she kind of expected since his attention was never on her in the first place.
Sirius, meanwhile, mustered up the courage to walk over to Remus and asked the latter's partner if he could dance with Remus at the next song, much to the two's surprise.
When the new song started though, Sirius was met with a light blush on Remus' face and eyes that couldn't seem to look at him straight.
Sirius held out a hand to him and asked, "May I have this dance?"
Remus in return grinned at him shyly and accepted. "Thought you'll never ask."
When Sirius finally decided to pull in him in a kiss the same night, he was definitely sure that it would be Moony he wanted to spend his life with.
The End