Some time back I analyzed the various traits in fictional characters that can push me to fixate on and obsess over them. It was rather detailed, which is something of a shame as I've since come to the conclusion that I can express the factors involved quite simply: I fall into orbit around (typically male) characters composed of some combination of psychological facades and emotional sleight of hand; an alternately self-sacrificing and self-destructive nature; and the capacity for intense and passionate emotion, especially if the emotion in question is a driving anger. Of course this has evolved over the years (only the fascination with heroic sacrifice in fiction has been with me as long as I can remember), and I've attached myself to several characters who don't fit it very well in the past (usually as a result of the text playing up their charisma and larger-than-life nature, which is a sort of wildcard factor in this science). But I need to be able to root them in those three things--and ultimately also in an essential nature that is in conflict with itself, which tends to manifest as self-destructiveness of some kind.
I don't always know who's going to do this for me. The situation I'm in now--of entering a huge and complex text with virtual certainty about what character and pairing are going to light me up--is an aberration and has a lot to do with the fact that I felt the sparks six years ago when I flirted with the tepid anime adaptation. Anyway, I named my PSP Tohsaka, so I'm pretty secure in this.
I was going to talk about the three ideas I have so far for Madoka Magica fanfiction here (one short thing that's Mami-centric and kind of Mami/Madoka, and two vague ideas for lengthier stuff, both complicated what-if AUs, one Mami/Kyouko and one Kyouko/Sayaka), but at this point I might as well save that for another post. Stay tuned.