Rochelle seems to thrive on having a target. She gets someone in her sights and then won't let go. She actually goes looking for confrontation, she said so herself to Philip. This is why drama follows her, she actually carries it with her. Joanne is out so on to the next victim.
None of the other housemates behave like this. They moan and bitch about each other but they don't have a personal vendetta against someone in the same way that Rochelle does.
She was determined not to like either of the new housemates and determined not to speak to them or even look at them or acknowledge their presence. She was angry at them for just walking through the door! But since Rochelle was able to use Catrin's minor tiff with Pauline as an excuse to bait Pauline, she is now willing to accept Catrin for the time being. As long as Catrin is her useful puppet.
I'm not surprised she's been like this with school parents. She will be like this with everyone. She is momentarily happy when her confrontations 'win', like how she celebrated 'winning' on eviction night but it's short lived. People like her never truly find happiness because they can't be happy for other people, instead they feel envious and threatened. It all comes from low self esteem.
Remember when BB used to have the psychologists on the after show. It would be great to bring them back again. The whole idea of the show is that it's an experiment to see how humans interact in a stressful environment. No one is immune.