Looking back, I realize they never really explained the full nature of the rift between Conrad and Marshall. I mean, sure, they didn't get along, dad was always busy working, etc. But Conrad literally vanished without a trace, causing Marshall to spend years searching with a private detective! You don't just do that sort of thing lightly, not unless there's a REALLY good reason. And given how they hinted at Marshall having been involved in Conrad's mother's death...well, I expected a bit more storywise.