WARNING: The following contains spoilers for Batwoman Season 3, Episode 4, "Antifreeze," which aired Wednesday, November 3rd on The CW.
While the latest episode of Batwoman Season 3 continues to focus on Mr. Freeze's cryogenic technology, it also drops several hints that another villain may be pulling some strings from behind the scenes. Specifically, there are a few moments throughout the episode that seem to suggest that Poison Ivy is influencing the actions of Mary Hamilton.
The previous episode of Batwoman ended with Mary being dragged away by vines after meeting with Nora Fries and her sister, and "Antifreeze" opens with her awakening in the middle of a park. She is seated on a bench, with vines receding around her. After stumbling out of the park, Mary is unable to remember anything that happened the previous night.
Throughout the rest of the episode, Mary is shown to be a bit distracted and off her game. In addition, she demonstrates a sudden fascination with plants, keeping one in her office and fawning over it. This plant actually ends up proving to be essential to the episode's plot, as it helps Mary develop a solution to unfreeze someone frozen by Mr. Freeze's tech. These moments throughout the episode pretty clearly indicate that whatever happened to Mary in the woods changed her, although to what extent is still unknown.
Poison Ivy has already been confirmed to appear in Batwoman Season 3, and previous episodes have already teased the eco-terrorist's debut. While Ryan Wilder seemingly retrieved a plant belonging to Ivy in the season premiere, a later episode revealed that it was a fake, meaning that the real plant is still somewhere out there in Gotham. This seems to indicate that Ivy has some sort of master plan in the works, and "Antifreeze" may just have shown the first step of it.
The synopsis for Episode 6 of Batwoman Season 3 hints at an unnerving discovery involving Poison Ivy, while also suggesting that she may be planning to take a new host. "Antifreeze" pretty clearly sets up Mary to be the catalyst for Poison Ivy's return to Gotham, but the reasoning for using Mary hasn't been revealed. However, in the context of the show, it becomes pretty clear why Ivy would want to use Mary - she's a doctor. The very first episode of the season saw Mary graduate from medical school with plans to revamp her clinic, meaning that Ivy would have an especially up-close connection to the people of Gotham.
In the comics, Poison Ivy has been frequently shown to use her plants to brainwash people, and it stands to reason that she's done the same to Mary Hamilton. Her exact reasoning for staying hidden in the shadows is still unknown, but clearly she has some sort of grand plan that she needs Mary to help her carry out. Given their large amount of shared screen time this season, it seems likely that Alice will be the one to notice that something strange is going on with her step-sister, but only time will tell if she will want to take down Poison Ivy or strike a deal with her. With Alice, there's really no way of knowing.
New episodes of Batwoman air Wednesdays at 9 p.m. ET/PT on The CW.