One of my characters has, possibly, PTSD of an event that happened in her backstory, and is quite paranoid and twitchy. I'd consider her crazy, but no one has ever boinked me about Asterisk, as when she is on station, she /does/ her job.. Albeit at the first sign of trouble she'll start barricading doors, building weapons, or hiding somewhere.
Does this rule mean no *pathic characters? A tweaked out janitor can still janitor, but isn't running around murdering everyone.
Yes, what Delta said is correct.