You and Cedric were a bit acquainted. Sharing a few classes here and there, he always smell like vanilla and fresh laundry. One of those classes you shared were Potions.

Snape partnered you both for potion making and you both happened to pick Amortentia (probably intentional by Snape). As the brewing nearly reach its end, you both decided to test it by smelling, hoping you both get a scent and see that it worked.

As both your noses smell the potion, you could almost tell who it was. Vanilla, fresh laundry, and broomstick — Cedric Diggory

"I smell..." He said out loud before he went still, like something struck his mind. Then, he said barely above a whisper; "...your perfume..."