How it happens fits really well. It's not disastrous. It's even foreshadowed heavily in the early series. I loved her end because RJ found a way to make it work without making her look bad (and Brandon execution of it all is really quite good). Her whole arc in the book is quite in character. Of course she's insane. They all are.



Hesselam is definitely more fun than Brandon's Graendal was. The time for fancy games is over. Demandred is the most impressive (except I never liked him much, so for me Lanfear stole the show), Hesselam is one hellish monster - she's not a perfect substitute for Semirhage (who would have been perfect to kill annoying characters in gruesome ways! There's a whole list I wouldn't have minded unleashing Semirhage on - several of which but not all make it out alive, alas), but she's sort of scary enough. She's clever and calculating in a Graendal kind of way if far more brutally efficient, then later she's simply a demon unleashed. She hands out quite the butcher bill. She gives a good idea how scary she must have been during the War of Shadow.

As for Lanfear, she wouldn't disagree with you about Cyndane, except about the "tamed" part. As well try to stop the Moon from rising at night than try to tame that one.

Of course we see more just how insane they all are. That was expected.