What do आप guys think about Terry? I have a feeling there is something not quite right with him.

He is messed up because he's been in the army and went to war. I think the things that he saw messed him up.
It's mentioned most in the episode in the firs season were its the DGD meeting at the church and Bill is talking about being in the war. Terry thanks hims because he has been through similar things and 'people dont understand'.
He's not a nasty person, he's intentions are good, he just goes about things in a different way.

He's a war vet suffering from 'Post-traumatic Stress Syndrome' (PTSD). They experience depression and other mood 'ups and downs' with added dementia and disorientation during stressful situations.

Thats why in season one when Malcolm's crew started causing trouble in the bar, Terry had a mental breakdown where he thought he was "under attack" and back in Fallujah.

Yeah! I don't think it ONLY has to do with the war. Not sure what it is yet?!

I also agree it is not just the war.People who don’t say much have a lot to hide.