In my head i've always suspected Geronimo kept Tersilla's costumes that her and her crew
wear to blend in. Here we see him dressing up in one she used to intern with at his newspaper.
Having found out he's gonna dress up in it Tersilla decided she would dress up as him to fool everyone.
(also have this idea that their secret lovers XD)

Tesilla/Geronimo © Elisabetta Dami
art by Logan
http://thesuitkeeper89.deviantart.com/