I went with magpie, although I started out more or less monogamous, became more polygamous over the years, and have been doing the lone wolf thing for the past year or two. But, yeah, 'magpie' seemed the most appropriate, overall, and more useful than ticking 'chimera', and then listing half the different options. I daresay that now I'm a magpie, I'll be a magpie for life. (It probably stems from my love of minor characters in small fandoms; if I don't keep collecting more of them, I have nothing new to read or discuss.)

Started off BtVS/AtS for quite awhile, then shared between that and Farscape for a bit, then became Farscape monogamous, then FS/X-Men... and then it kind of exploded into a million different fandoms. [/more than you wanted or needed to know]

As far as how long I've been in fandom, I went with how long I've actually been involved in interactive fandom, rather than how long I've been writing fanfic/reading tie-ins/et cetera (which would be 15-20 years).