He smirked at his older brother Sirius Black's expression.

Rage.

The girl Sirius had a crush on was to be wed to Regulus after he turned 18. Just to piss off his brother even more, he held the girls mouth up to his lips.

"Bonjour, amour, I believe you are my new fiance-to-be."

He said in a flirty tone. His plan was to make this girl so in love with him that she'd never look in Sirius' direction again. That would piss off his older brother even more.