I don't think Kagura's unsympathetic, I just think she's not so quick on the uptake. But take it as you will! :D

I wonder if Takasugi has worse scars, or if he was just more unstable to start with and so toppled off the hill of mental stability much more readily than the others. I mean, they all ended up pretty cracked in their own ways, he just ended up further along the spectrum of trauma.

Katsura is definitely quite intelligent occasionally - he's obviously able to keep track of all sorts of information and make good use of it, and plan campaigns and whatnot. He also is just the kind of guy can't see what's right in front of him. I think the scale of silly->moron varies pretty dramatically by episode. :D