The difference between Brian and Helen is that HE constantly went at them. I find it hard to believe that someone who went looking for it felt one bit antagonized.

He felt antagonized , she felt scared that's it really.
Both feelings are valid .

In one episode Marc admits that he antagonized Brian, Brian accused Marc and Helen of following him around when he was trying to stay away from them, antagonizing someone doesn't have to mean a verbal scrap, it can be a look, a snide comment that could be passed off as banter, it can be a smug look, there are many ways to antagonize a person, and how i see it is that Marc deliberately and knowingly and cleverly antagonized Brian, but we as the audience only see what BB want us to see, but nearly everyone who has gone into the house has had a problem with Marc, they can't all be wrong can they?

Ummm I'm not rising to the bait... are you saying all the other HM are making it all up then?

Yes, to be antagonized is simply to be caused to become angry. You could technically be antagonized by a tree if you really hated sitka spruce. But what did Marc do to antagonize him. If Brian chooses to become antagonized when nothing is being done he is in the wrong.