Hotch isn't emotionally demonstrative, but he has emotions. They're just tightly controlled. Gideon is really kind of self-centered, and for a brilliant profiler his social intelligence is absolutely atrocious. He seems to care about the people around him in terms of their jobs, and in terms of how they perceive him. Remember when Elle got shot? That whole; "She'll understand." All about how Elle sees Gideon; not at all about Elle as a person.

Back in Revelation; notice how Hotch is aware that Gideon won't be the one to teach Reid about handling the job emotionally? My thought is that that's because Hotch knows Gideon will break, because he doesn't know how to deal with the cases on an emotional level.

Really, of all of them, I'd say Gideon came perilously close to being a sociopath (or would that be psychopath?). Then again that might be because I never really liked Gideon. :-)