She's a bit crazy. Which is made clear from her general look and the fact that she's in an orange jumpsuit and handcuffed. Rather than boast about the finer details of the villainy that landed her behind bars, Frankie doesn't mention it, adding to the mystery of it all. So you don't know if she's just a petty thief or a seasoned serial killer. In apocalyptic times, does it really matter?
Frankie begins BRAIN DAMAGE in a very vulnerable position, being all gimpy and handcuffed and such. Still, she quickly establishes herself as a headcase by scoring the first, onscreen melee kill. Design must haves for Frankie included curly mohawk hair, smokey/black eyes, prisoner get up annnnnd a crazy grin.
Now, some of these go back to my days as a lazy 6th year at the now none existant St. Saviours High Schoooool, but let's at least try and keep the laughing at a minimum, mmmkay?