"I'm not worried. Not with you." He believes Lucifer wouldn't let him fail. He is much stronger than Istredd, he's not human, and he is probably far more graceful too when he needs to be. Istredd is generally more worried when it comes to people he is afraid to let down, but that is not the case in a dance for fun. Thus why he's never enjoyed dancing before. It's never been about fun.

A ... rockstar? It's not a term he understands. There are bards in his sphere, famous ones, but that's not what they're called. Also Istredd is completely unaware of them to the point if he did ever meet Jaskier, he would have no idea who he is, despite his fame status.

Music is not his forte, he's barely paying attention to what is playing now, outside of making certain they're on beat and not about to unintentionally crash into another couple if not moving in the right direction.