has fallen under the influence of a mind flayer as it has taken mental possession of her; she silently struggles against this mind flayer's influence. But that's probably the duke you're talking about.
I swear I read somewhere about a mind flayer tadpole nesting in Grand Duke Ulder Ravengard's head, but maybe that's me.
There are a lot of plot hooks in the Gazetteer, but it's hard to say which ones will get explored in BG 3, but I expect most of them will. In fact ever unique location noted on the BG map will likely be in the game I believe, like the Hospital.