It's the closeness combined with the accent that makes him realize who it is. Perry lets go of her hand, going to take a step back as best he could with her foot on his.

"Eponine?" Perry put both hands in the air, to show her that he didn't have any weapons in them. On his body was a different story, but wasn't that the same everywhere in here?

"I'm sorry! I didn't know it was you. I'm Perry, remember?"