[Ooh, a third person person! Espio is used to those! And in typical third person fashion, he is being entirely overdramatic. A rather satisfied smirk on his face at having made the kid flip out, Espio cycles through the rainbow before settling on his usual hot pink shade.]

Touchy, aren't you? Chill out. I don't care what colour you are. I know blue hedgehogs and red armadillos, so who knows what colour 'humans' come in?

[Yes he is going to stress the word. If Zim wants to pretend he's human for whatever reason, Espio has no reason to actually challenge him. Just... needle him a little.]