I actually chose to describe Rom as a sadist deliberately. He is someone who is getting joy from causing others pain. He isn't just doing the job, he's revelling in it, gloating about it. That's textbook sadist. It'd be naive to think this is a trait he's never shown before, or that this is his first job or opportunity to exhibit this trait.
It's also textbook bad guy, as others have said; instead of saying 'ouch' he could have justifiably said 'you sly wolf, you caught me monologuing!' Not much else to him. Clovis, at least, has a background that's been touched on, which gives him depth and motivations that one may not be sympathetic to, but can be understood and make some sort of sense (at least to him). Rom hasn't gotten that fleshing out, he's just a mustache twirler.
Edit adding: and that's not a knock on the writer. You can't flesh out every character. There's not enough time and it would drag the stories out impossibly. Imagine for example trying to flesh out the backstory of every red shirt in Star Trek before they get offed
. Some characters are needed simply to help do things to advance the story; sometimes that thing is dying.
Here's hoping Rom is weeded out of the story now that the one thing he's probably needed for - putting that thing on Kat - had been accomplished.