What's that thing called, where a character has a trait that contrasts their usual one? Gap moe?

Eris nails the annoying brat trope in a way that cracks me up laughing, similar to how Saika (Oregairu) nails the trap trope. It's like a gag to hear that annoying squeaky voice, with her popping out without any delicacy. It's those girly moments that offset it, like showing up in a fancy outfit.

I dunno if that gap moe applies to Rudeus's pervy nature, but that gets me to crack up too. The voice narrating his thoughts might have something to do with it though. The Hilda scene... XD