My own fandom history is peculiar. I discovered internet fandom via Harry Potter but it was always so effing huge and when the tiny fansite that I had followed from its start ended up closing down and I no longer had a manageably miniature way of participating in forums, reading and reccing fic, keeping up-to-date on news, etc. I basically let go of fandom. (This was in the Days Before LJ so I had no idea what kind of fandom went on through LJ comms!)
Also through Harry Potter, though in a very different way, I ran into the fandom that would become the love of my life, my One True Fandom, if you will: Diane Duane's Young Wizards novels, which I picked up for the first time when in between Harry Potter novels and fell for in a flash. Years later my passion for HP has faded but YW and I are still more-or-less madly in love. It helps that this is a super obscure fandom, easy to keep up with, very supported by the author who runs a discussion forum over at her personal website, and all of the people in it are really kind and supportive (though you'd expect this out of a fandom whose canon depends on the belief that any anger or unkindness, however small, speeds up the heat-death of the universe and plays right into the cosmic antagonist's hands). It is the fandom through which I have made my only non-RL LJ friends!
The point being, I've flirted with other fandoms, but Young Wizards is really my home, and has been for at least the past seven years. I've read all the novels multiple times, I fall asleep listening to the audiobooks on occasion, and characters grew and changed over time and along with me. And this is really the only serious experience of fandom that I have.
Which is why I'm suddenly finding it frustratingly problematic to get my head around writing fic for another fandom. I posted before about how much I loved Scott Westerfeld's Leviathan series, and I really think that it could be a brilliant second fandom home. It's the first fandom since Young Wizards where I've said, "This is something I want to be a part of for a while, not just until the obsession wanes." But my experience coming into the series is so totally different from what I had with YW. I read all three books in the trilogy within the past four months, they haven't been a part of my mental landscape for very long at all, and as much as I want to write ALL THE FIC for them, I find myself feeling weirdly blocked by a sense that I'm just not ready yet.
All of this is an incredibly long-winded way of asking: How do you get yourself to the point where you feel comfortable writing in a new fandom? How do you iron out things like characterization and tone and headcanon and backstory? Do you read a lot of other fic for ideas or do you tend to read and re-read the source material? Is there some magical secret that I have yet to encounter?
Part of the problem is that Leviathan is also a small fandom, but since these are YA novels most fandom participants are probably teenagers...not that this is inherently bad, but it does mean that the kind of discussion I would expect from an LJ comm is a bit lacking in the one active comm for the series... Another part of why Young Wizards is awesome is that a lot of current fandom luminaries are people who might have been teens when the first book was released in the eighties, but are now obviously more mature and care about having philosophical conversations about the nature of the world and the characters, etc.
Guys, I just want to write stories where a girl dressed as a boy and the boy she's in love with go around their alternate universe Europe having adventures and being awesome -- is that too much to ask?