Am I the only one who *didn't* interpret this as poison? The potion was called an "age regression" potion. I thought she was trying to save him and it just didn't work? If she just wants to give him a poison to make him fall asleep and die, she doesn't need especially exotic ingredients for that.
I also read it this way. I think that the following scene, with his family, is just her taking advantage of an opportunity that ended up in front of her.
To sum it up, I think:
* She didn't want him to die and actually tried to save him.
* Her line, "Well played" to the Inquisitor who tricks her wasn't about being caught, it was about her appreciation of an excellent player of The Game.
* When he died, she used the subsequent events and discussions to better her position as best as she can. Again, she's a master of The Game.
* Her appreciation when you help her is obvious and seems genuine. It's also why she pledges her new support in your direction as well.