Theodore thought about what she was trying to do for a moment. It was certainly better than he'd originally feared. He knew what could happen if you tried to mess with someone's mind. But this didn't seem to be that, fortunately. Magical Paxil, or something. It did - somewhat - beg the question why the person in question wasn't trying to just seek out a non-magical remedy. But then, as much as administering home remedies was firmly in the camp, and the prerogative, of the magical. So also was seeking a magical solution that might be solved without magic. Lumos and a light switch did the same thing, etc. Wizards by nature were something of showoffs.
"I think, to start, it's a good thing we're not trying to actively control or deny the other personality. Again, I'm no psychologist, but I get the feeling that, well, the Other, for lack of a better term, might not react so well to that. But I think it's worth giving your friend's brother some calm and some piece of mind." Ouch, maybe a bad choice of phrasing, there. Theoretically, after all, he seemed to have at least two. Pieces of mind. Yikes. "Anyhow, I'm not familiar with infusing crystals using potions, but, perhaps we can find something which is rather benign on its own, but might otherwise amplify magical effects or potency?" He suggested, trying to think of such a thing. "Instead of possibly co-mingling two magical effects which we think are similar but instead produce some unintended third result.