From today's episode, she looks ready to kick ass and take names. In the beginning she seemed so timid that she would be scared by her own shadow. She has grown and changed so much, I am thinking she cannot still be 18 surely?
But it is hard to track how much time has actually passed in the GG'verse. By all accounts, she was with the circus for a few months at least. And the relationships she has formed do not grow to such depth overnight. Any guesses as to how much time has passed, and how old Agatha is by now?