This was fun :) I like the dialogue - also, Katie for the win!

That Quidditch cup"...Quidditch cup in my hands!" might want to be changed to House Cup, because that's what the students play for, I think, not a Quidditch Cup. That's like the national teams.

"...by Merlins pants!" should be, "...Merlin's pants!"

"...when you loose and..." ought to be, "...when you lose and..."

I liked how Katie was so clever about getting her wand back from Flint by kissing so she could get close enough to it.

The way Flint came in to bully her in the first place for being on the winning team was a great idea and really showed him to be the sore loser I always thought he would be.

Great story! I love this couple!