"All I know about mermaids," as she lights a cigarette, setting her apart from probably not as many fairies as you might first think, "is that they go in the sea, and I don't."

Making it sort of quibbly to be so determined about the difference between her and a mermaid, due to the fact that she isn't completely clear on what that might be anyway, but it's one thing she does know and therefore it matters.