Gregor first appears in the New 52 issue, Batgirl #2. He and Barbara are seen enjoying lunch date together, then move on to the park. In their conversations, it is revealed that Gregor is Barbara's therapist. He also mentions that seeing his client socially isn't exactly ethical. In the park, Barbara talks to Gregor about how her memories are so painful, and she doesn't understand why, of all people, she received a miracle. She asks him why the questions are so painful, and Gregor responds with "Because you want to know the unknowable."
In the third issue of Batgirl, Barbara implies in an inner monologue that she and Gregor have stopped seeing each other.