I think that Valaste needing a long rest after the quest makes a lot of sense.
Sure, Valaste seems like a collateral to screw with Shalidor, but as a mindscrew, I'd find Shalidor's reaction terribly... dull. How very Shalidor. Just like the last time!
And why screw with one mortal when you can screw all three at the same time? (Or two, if your character only cares about power)
Shalidor hasn't changed. He still ignored the fact that the quests has been taking a toll on her. Even if you chose Valaste, he hadn't even apologised or acknowledged his role in this. And if you chose power, his regret was... Letting the madgod win.
Not the lost of a brilliant mage, but it's losing to the madgod again that really hurts him.
And Valaste probably heard that, in the spell fog, the same time when she gets a personal experience of how it feels like to be taken by the Madgod because of someone's choice, whether it's for power or for the greater good. Now Eyevea's past is no longer a secondhand story. And with everyone else thrilled about having eyevea, she is left wondering:
What is this legend that I looked up to? Oh, and she truly enjoyed learning under Shalidor too.
Well maybe Shalidor changed. But Valaste at one point said:
"Well, look on the bright side. You're still upright on two legs. You're not inside-out, or bright purple, or afflicted with new, angry limbs. It could be worse."
So, what if this worse hadn't happened on her, but the new member? A mere adept?
And then things moved on. Mages came to Eyevea. While she still absolutely remembers the Fog, and one might have to sacrifice themselves for the greater good. That's what she did to the adept as well. And that kind of being useful... Isn't the same as truly belonging.
Yeah, that's why she's a shell of who she was. But also I guess the dev never coded any sequel quest lines for her.
