I think it was the illness. Even without the illness based on the first games ending and the fact that Arthur was not mentioned or existed within it I was pretty sure I knew how rdr2 was going to end before I started but the illness gave it such a somber tone. Arthur recognized his mortality and really started to reflect.

It’s been ages since I played rdr1 but as far as I remember John was more “I’m doing this to be done, for my family!”. The tone was much lighter as a result even though there were moments that were heavy. And the characters weren’t as developed so I didn’t care as much. Dutch was just a fucking monster in that game, bill and Javier were just props. But rdr2 fleshed them all out so much