We all know Mike. He's a proto-bro. He's really rude and usually totally inappropriate, but still a lot of fun to be around... until he's just not anymore. Yes, he always says the wrong thing. No, he has no verbal filter whatsoever. Perhaps he doesn’t even have a conscience. Despite all of these things, Mike is still entertaining and even somewhat (and that's a loaded "somewhat") sympathetic.
We know that Mike is a veteran, and that he’s due to come into a large inheritance one of these days. Until that happens, he’s just aimlessly drifting through life in one long offensive, sometimes comic, sometimes tragic, drunken binge. He has no apparent employment, and simply lives off the allowance his family grants him, as well as the kindness of his friends:
"How did you go bankrupt?" Bill asked.
"Two ways," Mike said. "Gradually and then suddenly."
"What brought it on?"
"Friends," said Mike. "I had a lot of friends. False friends. Then I had creditors, too. Probably had more creditors than anybody in England." (13. 31)
Unlike Bill and Jake, he never moved past the war, even on a superficial level—he occasionally relates stories about his ridiculous exploits as a comically inept soldier. We get the feeling that Mike’s lack of focus in life relates to both his background as the scion of a wealthy family, and the sudden disappearance of any sense of purpose once the war ended.Mike Campbell Timeline