It helps in my case that I'm relatively new to the whole fanfic thing, and even to Buffy fandom. (Not as new as some, but there are episodes of Angel I still haven't seen completely.)

But...I don't know how to describe it...I see ideas, and they connect in odd ways, and I ask, Did Joss ever do this? And if the answer is no, I write it. Usually, in fact, the answer is no.