"What is Hermione wearing?" Heather asked me.
"I don't know," I said. "How can you even see what she's wearing when she's standing next to that guy?"
"That guy" is Ezra Miller, Emma's co-star in Perks of Being a Wallflower (which I haven't read; should I?), and he seems like a delight:

That isn't me being sarcastic. He trained as an opera singer to overcome a speech impediment...and ended up singing at the Met. He played Kevin in We Need to Talk about Kevin, so he's on SWINTON's Christmas card list. He said the following recently: "I have a lot of really wonderful friends who are of very different sexes and genders. I am very much in love with no one in particular," the latter of which is a phrase that sounds like it ought to be a very good pop song that I want to sing really loudly in the car. He apparently is part of a very in-demand mariachi band and left his urban sombrero in the car. I sincerely feel like if you got caught in an elevator with him, you would leave that elevator with plans to go get omelets with him. I like this kid.
But let's look at Emma's dress. Alone:

I kind of feel like it's two cute dresses melded together into one weird dress that I might like even though it also makes me feel like I'm about to have a seizure. Like the most memorable cocktails, really.