I've been writing about someone with a Multiple Personality Disorder (or whatever it's called now). The original character is the dominant personality, but she's the secondary one. (As in the second character was the personality she was born with). During the first character's (second personality) outings she got addicted to nicotine. My question is: does this affect the second personality, too? I was thinking it was about the chemicals more than the personalities themselves. So like when the second personality is out and about, she has withdrawls and doesn't know why.
Does anyone know if this is common? I'm trying to be as accurate as I can.