I spent a fair bit of act 2 trying to work out if he was angry his daughter had been converted to Selune or become a lesbian, and suspecting he did the no daughter of mine thing and kicked her and she died and he blamed himself leading to his betraying Shar, cursing the land and joining the absolute. But then at the end of act 2 she was just ALIVE with no warning or explanation. It was weird but cool and paid off the set up for Aylin while also giving her a happy ending when it looked they were going all tragedy and really, shes already been tortured for 100 years getting a happy ending is more a twist than just, more grimdark happening.
Isie is useful in the final battle, she has an AoE healing effect

Minthara is the best character and she NEEDS to be recruitable if you side with the grove!
Also- I support the important thread in the suggestions: Let everyone in the Party Speak