Well, both of these rely on each other, so first I'll point out that what Mab did to Harry was stupid, dangerous, and necessary. When Harry realized what had been done to him, he had a total freaking meltdown in Michael's shed. He literally did not understand the words "blasting rod."
That was after a day. Imagine what it would do to a person if it came apart after a month, or a year—suddenly realizing that you were not who you thought you were for an extended time. I think you'd have some fundamentally fractured psyches.
Oh, the realization itself would be really unpleasant -- but I don't think there'd necessarily be lasting damage.
I mean, we see the Merlin and Luccio in Changes after they were mind-warped for
years by Peabody and they don't act messed up. Luccio even got body-swapped by the Corpsetaker, and she's still quite functional (it did give her nightmares -- but she was way less affected than Rosie and Nelson, from a way more fundamental attack, and one that was malicious rather than well-intentioned).
For that matter, Harry got his mind invaded by the Corpsetaker in DB and Molly and Butters got possessed by the Corpsetaker in GS. They don't show aftereffects like Molly's victims.
The evidence seems to show, IMO, that those kind of aftereffects only happened because Molly had no idea what she was doing -- the only other times we see serious, lasting effects are from actually having big chunks of your spirit eaten (Murphy and the Nightmare in GP, and Justine and Thomas in BR).
I don't think Harry was ever tainted to begin with.
Sure he was - Ulsharavas (early in DM) can detect the taint on him.
Yeah, and she's been entirely stable since Changes, right? What about all of the murders she committed as the Rag Lady? She has a meltdown explaining how easy it is to kill crooked cops with magic, and it's pretty obvious she's messed up, and not just from screwing with Harry's head.
Molly is crazy, sure, but there's a bunch of other factors playing into that -- her guilt for Harry's death and her need to fill his role would be quite enough to severely mess up a lot of people, and there's also her heightened emotional sensitivity and the psychic-shock aftereffects of Chichen Itza.
I mean, Molly was protecting Chicago, but still outright killing people with her magic
We actually don't know that, it's pretty ambiguous, since:
- some of the Rag Lady stuff was Lea
- the turtlenecks are indistinguishable from normal humans once they die, since the Fomor implants turn into ectoplasm
- Molly's talents aren't particularly conducive to killing directly with magic - being under a veil and stabbing someone doesn't break the First Law, and I don't think the illusion-of-a-gun thing that led to getting someone shot would either. An Alpha-style werewolf killing in wolf form or a Warden binding someone with a spell and then killing with an enchanted sword don't break the First Law.
Yes, but remember when Harry would have died from his first encounter with the Corpsetaker but for Gard's intervention? The reason he almost died was because of lack of proper training against mental attacks.. The reason for his lack of training weren't the usual ones, i.e. Harry's own laziness or lack of exposure to it because of Justin, but because the Council feared and prohibited any form of this magical training beyond the minimal defensive type. So the Council prohibited it even if permission from the two parties was granted..
Yes. According to Harry in GS, that was later changed (probably in response to Peabody's mind-warping the Senior Council and Wardens, although maybe it started earlier -- maybe Luccio lobbied for it after her experience with the Corpsetaker).
