Other characters I find much harder to get to grips with. I would once have said that Jenna was probably the hardest B7 character of all to write, though I've since found a door to stick my foot in. As with Cally, it took a bit of figurative carpentry on my part, but her initial antipathy to Cally was a useful lead. Not very flattering, true, but I've always found the murkier depths of the mind to be far more interesting than the bright and shiny bits, and a character is all the more interesting for his or her flaws. From that slender thread I wove a whole tapestry of Jenna's past, though I've yet to get it down in a complete story.
Some characters are just plain impossible.
I have actually written a Gan story, which I took on mainly as a challenge, but he soon got overshadowed by an original character of my own devising. Gan ended up just sort of being there, as a line of argument for the broader philosophical themes of the story. Dayna is also a problem, which is odd because she has the most detailed background of any character in the series, but it doesn't offer much to get a hold on. Or Gan for that matter. Soolin ought to be a real pull for me.