Isis makes an interesting connection between dopamine (love 1.0), oxytocin (love 2.0) and fandom. She points out that the intensity of crushes on stars or fictional characters feels like the rush of romance -- and is probably fueled by the same neurochemicals. She thinks such crushes may be a good way of getting that chemical fizz without endangering that oxytocin-rich long-term relationship.
I wonder whether my approach to fandom is related to my oxytocin-mediated relationship - I'm looking for that dopamine high, that fizzy love feeling, so I get these big crushes on characters (or, ahem, actors, or even other lj-people), and I thrill to the first-time story, the new-love story. (Which is why I think fandom is a good thing. If I wasn't involved in the relatively harmless pursuit of fictional characters, I might be out there pursuing real people. This way, I get all hot and bothered, and then bother my husband. :-)