Physic is the physician of the Black Swan. In Nightfall, she is revealed to be Livvy, Quinlin 's wife. Quinlin and her have a rickety relationship, fighting often. Livvy apparently was supposed to file a match fail, the elves' version of a divorce, but hasn't, so they're still together.
Physic was the person who helped Fitz after he was impaled in Exile (Neverseen). It was said that Physic was in the collective until she couldn't always be there, so she gave her place to Juline Dizznee, as she was her doctor. It is said that the reason she gave up on being the Collective is so that she could focus more on medicine. This is because when Sophie had an accident in the Forbidden Cities with limbium, something she is allergic to. The story doesn't go into detail about the topic, but it had something to do with Mr. Forkle and Physic.
When working for the Black Swan, Physic wears a mask to conceal her appearance.
She has black skin, tiny breads woven into her hair, full lips, and a softly rounded nose.
Spoiler Ahead Edit
In Nightfall, we learn that Physic is really Livvy Soden, Quinlin's ex wife, but not really, because they haven't filled out the divorce papers, aka match-fail paper, because of the shame that would bring.