"There are lots of potions to lower resistance and compel truthful answers, and I was a top student in Professor Slughorns Potions Class, second only to Severus himself. I do apologize for feeding it to you, but time is limited, and I needed to be sure that you were not planning to harm the Black Family. It was also important that we come to an understanding. I swear on my magic that I will not use such a potion on you again without your permission. I also swear that I will not use; or permit to be used by another, the information you have provided me, without your express permission." Her wand glowed and Harry nodded.