Umbridge, of course, was oblivious to all the cross-currents, and concentrated, instead, on quarrelling with Dumbledore. Of course, our Headmaster was miles ahead of her. When the toad demanded to know what would happen when she hired another Divination teacher, who would need Trelawney's rooms (in a castle this size? I could find dozens of rooms that aren't being used for anything in particular, and there's whole areas I don't know well!) Dumbledore just explained that although Umbridge had the right to hire new staff, that only applied if he, as Headmaster, had not been able to find a suitable candidate, and that he had found one. When he introduced our new Divination Professor, you could have heard a pin drop. It was Firenze, one of the centaurs from the Forbidden Forest.