I think anyone who has a relationship bar can be romances eventually like Harold and rhot have them but no romance has been added. Blake has one so I'm pretty sure he will have a romance route it's just gonna be either kinda complex or super simple. (Assumptions based on maybe he's quiet cause of trauma or you ask him out and he says yes, just guesses because of how he acts.)
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...)