Well, not really belligerent, at least not in my case. I'm not asking help (since I know my characters best and any advice I might follow could be untrue to the characters) so much as asking how other people go about it. If any of you have ever written a couple of characters that starts out seemingly unable to stand the other, how did you reflect that in the writing? Disagreements? Teasing? Causing each other mutual but insignificant wrongs with ensuing over-the-top and disproportionate anger? Share it!
It would really be the same way you'd show any two characters who don't like each other or have complicated feelings for each other interacting. You could show actions and thoughts that are at odds with what the character has actually said.
Haven't written anything like this because if a man is attracted to a woman, it's unlikely he'll be a jerk towards her, or if he is, he must be an all-round jerk (like Sterling Archer in the Archer animation series). Men pretty much just want to get laid, and a bitchy man won't. Women can get laid even if they're bitchy.
Sexual tension exists when the two people in question are totally focused on each other. It doesn't really matter if they annoy or anger each other, as long as they completely engage the other person's attention. Other people in the picture just aren't important. That's the giveaway. Focus. If one is able to ignore or forget the other (by ignore, I mean really ignore, not just pretend to ignore!) then there probably isn't any sexual tension in the relationship.
