So, the mentality has to happen before the magic does?
Surely the Lawbreaker stunts are the exact opposite of this? Magic changing who you are?
Assuming that Lawbreaker is merely the most extreme form of change makes sense; yes, you can become a psychopath by killing people, but also more emotional via fire etc.
The place were it would really matter is with Sponsored Magic; hence Harry's fear for both himself and Molly re: Winter.
This would be a sneaky way to get around the 3rd Law, rather than modifying an apprentice, order them to perform spells that inspire the changes you want. Since they are choosing to obey, it's a natural shift.
Of course, they're going to be really bad at spells that are contrary to what they are - hmm, Molly's bracelet is now disturbing. Especially given most of Harry's training was from DuMorne, and that's where he'd be getting the techniques from.
Oh, sod. DuMorne wanted Elaine and Harry in the sack together, so if Harry has been teaching Molly spells DuMorne designed for Elaine, that would explain why a childhood crush has lasted for a decade....
