My parents are/were both narcissists and alcoholics. I haven't read that much about them being companion disorders but I do seem to come across a lot of narcissism in AA. I have a friend whose mother could be my mother's long lost twin, she's (the mother) been diagnosed as border line personality disorder. What ever you call it, it's a sad state of affairs when your parent or spouse can't love you enough to want whats best for you, but must always want what's best for them.
A great book on this topic is, "Trapped in the Mirror."