the fat bandit(Barrel) is included to the relationship log, there may be future update abt him. only way I know to increase his relationship is him visiting your home(Bareshade) at night and choosing the obvious choice to pleasure him.
I prefer the muscular bandit. Barrel was never really my type. ^.^;
I'd give an arm and a leg to be able to have a submission and/or domination route for him as a permanent lover/partner. It'd be cool to be able to slowly break him by defeating him and choosing the sex option. As it stands he is just permanently only a top and only interested in male characters if they use tease skills (or so it seems). Course, I'm fine with him remaining only a top, but yeah...would love to be able to do more with him as a character.