Once someone's interested in something it just takes a teensy suggestion (preferably from non-family, that's more objective) that they'd possibly like to read something else.

My friend is a Harry Potter fanatic, she called me a parselmouth once because in this one fiction I'm writing, I'm part Dragon and can therefore talk to snakes. I don't think it counts as parselmouthing if you're actually part wyrm yourself... I identify much more with Hermione, actually.

I'm not addicted to the Potter series, but it's good fun and I'll probably pick up a few phrases because my friend says them. *g*