Ghost wasn't really one for friendships. It is insanely hard to even get him to look at a person. His respect must be earned. It has only been acquired by a slim few. And they had to work insanely hard to get to that point. Ghost would only salute people if he had to because he respected their rank. Not them. Other than that, no one else mattered. He did not give a shit. He does love some good banter though. Especially dark humoured banter. It gives him a good cackle.