After Nettie poisons CHARNAME (Rude!) after I failed all my checks, I used Blessing of the Trickster on Astarion and pick pocketed Nettie for the cure. Once I consumed the potion, a conversation cut-scene began immediately. Nettie began talking as if I had passed my checks and it was HER that was giving me the antidote. This seems strange to me that she wasn't furious that I obviously stole and drank the vial.

She also made me swear to poison myself if I feel I should turn. These Druids be crazy!