You and Pansy, Draco's friend, are BIG enemies since kids. Since your parents are also enemies, they raised you to hate each other like them. Funny, huh? But yeah...
One day in your fifth year at Hogwarts (whatever house), you with your friends and Pansy with her friends walked past each other at the Viaduct. You and Pansy shared a disgusted glare as you both walked past each other with despise.
"Bitch..." Pansy muttered under her breath and you just looked back at her judgementally.
But that was broken by Draco just chuckling next to her, turning your attention towards him. The hatred in your gaze towards Pansy faded away as your gaze softened to Draco, your crush since the first year. Sadly, you have to despise him as well since he's a Slytherin, and Pansy's friend.