- "So, I swear this began with me offering water and Band-Aids, and the next thing you know, I'm the Meredith Grey of Sherwood Forest. I'm sorry if stealing from my med school makes me a bad person."
- "It doesn't. It actually makes you deeper than I thought."
- —Mary Hamilton and Kate Kane[src]
Over a decade prior to 2018, Jacob Kane and Catherine Hamilton got married, and Mary met her step-sister, Kate.
The kidnapping of Sophie Moore
In 2018, she attended the switching of the Bat-Signal with her mother, Catherine. After Sophie Moore was kidnapped at the event, Mary called her step-sister Kate to come home. Mary organized a surprise welcome-home party for Kate, during which Mary talked her head off. Kate asked why she called her, and Mary revealed that she accidentally discovered a box of pictures of her relationship with Sophie, and thought that she would want to be in Gotham for her. Mary was pulled away by her mother to take a photo with a councilwoman.
The following day, Mary was working at her clinic when Kate was left on the doorstep. She was brought in and Mary helped stitch up a wound on her arm, when she explained all about the clinic, while also tending to an old man. Later a member of Alice's gang was brought into her clinic, and has somehow confessed Sophie's location.
Despite coming off as a ditzy socialite, Mary is a kind-hearted woman who will go to any length to help those she loves. Due to the close bond she shares with her step-sister Kate, she's one of the few people who can talk her around. However, Mary also has a bit of an animosity for Kate not really being her sister.
- Medical knowledge: As a medical student, Mary had a substantial amount of medical knowledge, enough to operate her own yet illegal clinic.
- Keen Intellect : She runs her own clinic without getting caught.
- Gun: Mary carries a gun so that she can protect herself.
Behind the scenes
- In the DC Comics, Mary Elizabeth "Bette" Kane is the original Bat-Girl and served as Batwoman's sidekick and Robin's counterpart. Growing up she would adopt the alias Flamebird (and later Hawkfire) in response to her counterpart's development as Nightwing. In the comics she is Kate Kane's younger cousin instead of her step-sister.