I haven't seen a relationship bar for Rhot yet. Seems odd considering how many times he's fucked me, but then again, the guard has fucked me the most of anyone and it doesn't seem to be progressing his bar anymore, so maybe that's just not what Rhot wants.
On my first playthru, Rhot's bar showed up after finishing the lizard branch.
On my current playthru I have gotten banged by him a few times (warrior lust 8) and I want to see if thay affects his affection levels when I finish the chapter.
I have also captured and dominated (okay I subbed for him till he hit 50 then dominated him till he hit 50) the big red lizard guy and his affection gauge was like 30.
(Hoping there might be special "My memories are hazy of that time but I remember vaguely of being with you..." You know, even if his mind forgot his body remembers...)