WARNING: The following contains spoilers for Batman Secret Files: The Gardener #1, now on sale
The Gardener -- aka Doctor Bella Garten -- is a known eco-terrorist whose relatively recent debut has repeatedly hinted at her connection to Poison Ivy. She's thrown her lot in with the heroes of Gotham during Fear State in an attempt to rescue Ivy and restore her to her true self -- but it turns out Ivy's not the only major DC character the Gardener has a secret history with.
In Batman Secret Files: The Gardener by James Tynion IV, Christian Ward, & Tom Napolitano, the Gardener is revealed to have been a former student of Jason Woodrue -- and was also an associate of another hero connected to the Green.
The Gardener's origins are fully explored in Batman Secret Files, which reveal more about her life -- starting with her time with her parents before they died, and how she was taken in by the groundskeepers of the military base she'd been raised on. Developing a dee-seated love for botany through this, she pursued a career in science -- focusing on plant life. Eventually, she became intelligent enough to catch the attention of the United States military, who invited her to join a graduate program focusing on Experimental Botany. The class was run by Jason Woodrue -- the future villain known as the Floronic Man. At the time, he was still a surprisingly convincing professor, inspiring discussion and invention from herself and others.
While the Gardener would go on to develop her own ideas -- giving plant-life the ability to evolve into predators so they can more readily defend themselves -- others began their own experiments. This included Pamela Isley, the future Poison Ivy -- who focused her own research on pheromones. Among their peers was also Philip Sylvian -- who would go on to have a connection with the heroic Black Orchid. But perhaps most intriguing were Alec and Linda Holland. Described as the "stars of the program," their bio-restorative formula could have gone on to save countless lives. But they ultimately left the program, unwilling to simply hand it over to a military that would likely weaponize it. It wasn't long before they seemingly died in a laboratory fire.
However, in reality, Alec's mind would end up fully connected to the Green, and he would go on to become the Swamp Thing -- one of DC's most powerful figures connected to the Green. It's a perfect little connective piece for the Gardeneer, putting her in the same class of thinkers and dreamers -- both good and bad -- that would go on to define the future of the Green in the DC Universe. In terms of adding someone to the tapestry of the DC Universe, it's a fitting addition. It's clear that the Gardener enjoys her relative anonymity, having left Woodrue's classes to pursue her own mission but openly electing to avoid the superhero community when at all possible, giving her a uniquely grey worldview in the middle of the typically black and white morality of superhero stories.
She only visited Batman after the events of "Everyone Loves Ivy," explaining to Batman how she created a secondary Ivy out of hope that one day, the two halves would be united and Poison Ivy could go on to save the world in a way neither of them ever truly could. This all sets her up as a unique wild-card, whose connections extend beyond the Bat-Family and their rogues. She could go on to appear in future Swamp Thing stories, and could likely present an intriguingly unique perspective on the character. This revelation about Gardener's past opens up plenty of avenues for DC to utilize the character in new ways, making her a more exciting character going forward.