[Wow, the people of ancient Grecian myths (or was that Roman?) are kind of... stupid. Did they not have any concept that "thing in reflective surface am not real thing?" Maybe Narcissus was a budgie.

Whatever. The story's not even important. They sip their tea, clear their throat.]

So in a hypothetical situation where one defies Her Majesty and crosses over... they get erased. Okay. Is the real person still stuck on the mirror side, or are they booted out automatically?