Finn was there and he looked exactly like this, except his tie matched Charlie's dress. There is probably even a picture of him somewhere in that exact pose. He came with Charlie, who he was absolutely starry eyed for all night. He gave her the top corsage, though the ribbon on it was black. He's not much into dances and school spirit at all, but he's gone outside of the box a lot this year and found himself enjoying it, so he wasn't curmudgeon or anything like that. He definitely danced and he definitely enjoyed himself.
Also, if Charlie got prom queen, he 100% stole the tiara at some point to wear. Sorry, these things have to happen. It's the perks of being the queen's mistress.