Yes, I agree that once he can say he "lives" there, then he is on the hook for his half of it. I'm just pointing out the alternative theory that has was in fact blindsided with this rent issue. This is why I was asking if there were pre-determined living arrangements discussed etc. Personally, I need my own bed at least a few nights a week, so I've never crashed with someone a month straight.
But I do believe the like I said, if you go along on the roadtrip, then help out with the gas (in this case, food and other consumable items that are shared).
But also, 34 with a good job and living with mom is a little weird. . .