Starlight, he might answer, and smile just-so. Spiders, if he was feeling cruel, but the urge comes upon him less and less. They drift together, enough space between them for comfort, and Thranduil does not smile when Corvo flinches.

"You mortals change so quickly." Not a condemnation, just an observation, and apparently it means he'll let Corvo rest. "I have not found him yet today. I fear some thing has caught his eye and he will play with it for the rest of the night."

Rather than dance and enjoy himself- but the Outsider prefers solitude, or is at least accustomed to it. Perhaps that is what he needs for a fun night as opposed to-- Thranduil's inclinations.