I have never seen Firefly, but this definitely has be wanting to give it a go. I DO know what Companions are, though, and oh, to be a fly on the wall while Crowley tried to explain that without getting Aziraphale jumping to a wrong conclusion...

Def agree with the above commenter, this has me hooked in and makes me want to know EVERYTHING. (But I shall settle for grabbing the series on DVD when I can)