Henry Dobbins is that gentle giant that you see in pretty much any movie or book about a group of people. He's big, so he's the machine gunner of the group, and you'd think that he'd be pretty scary as a result. He also happens to be the one who's soppy enough to carry his girlfriend's pantyhose around his neck for luck (keeping them even when she leaves him), and he's the one who effortlessly connects with the Vietnamese.
When a girl is dancing after the death of her family in "Style," Dobbins is the one who instinctively understands her, and when Azar starts to mock the girl, Henry threatens to throw him into a well. The monks in "Church" call him "Soldier Jesus" for some reason that no one really gets, but it probably has something to do with the way that Dobbins is simply incapable of making enemies among the civilians. He can't do it. He identifies with them too quickly, too easily.
He's not too smart, but he realizes that. What's important to him is being decent to people.