The loss of Ruby Rose as the Arrowverse's Batwoman has already put the show into a tailspin. This was only made worse, with the recent news that Kate Kane will be written out of the show entirely, a decision that, so far, has been extremely controversial among the fandom. It isn't helped by the fact that the only real information about the show going forward is that the new protagonist will be a young woman named Ryan Wilder. This is a completely original character, who has no ties to the comic books.
It's possible, however, that the casting notice for Wilder is actually a cover for a character from Batman lore. This is bolstered by some of the elements in her description. Here's a look at some of the heroines that Wilder could turn out to be.
Holly Robinson
The casting description immediately led some to believe that the Ryan Wilder character is actually Holly Robinson. Robinson was created by Frank Miller and David Mazzucchelli for the iconic story Batman: Year One. There, she was an underage prostitute who was friends with Selina Kyle, the future Catwoman. When Selina became Catwoman, Holly became a sort of sidekick and partner to her, acting as both Selina's Robin and her Commissioner Gordon. When Selina had her daughter in the Post-Crisis continuity, Holly also subbed for her as Catwoman.
It was later revealed that Holly is a lesbian, which would match the character description for The CW's new Batwoman. Ryan Wilder's seedy past, as well as her tendency to feed kittens, is another similarity to Holly. Despite this, this character taking the lead in the series would be a bit out of left field as Holly has never had any real interaction with or connection to Batwoman.
Harper Row
Harper Row is one of the newest members of the Batman Family, having been introduced during the New 52 by Scott Snyder and Greg Capullo. A streetwise woman from the wrong side of the tracks, Harper's rise to heroism originated with her stealing for her family and beating up anyone who would try to harm them. She also had a deep desire to work with Batman, which he eventually allowed, albeit begrudgingly. When she officially became one of his crime-fighting partners, she eschewed the typical Robin moniker, instead creating her own alias: Blue Bird.
This rough upbringing mirrors what has been revealed about Ryan Wilder. Meanwhile, although Harper Row from the comics isn't a lesbian, she is shown defending her brother from gay-bashing. Plus, the version of the character from Young Justice is bisexual. The character's recent introduction into the Batman mythos also makes her more malleable for a loose TV adaptation.
Helena Wayne/Helena Kyle
Helena Wayne was the original incarnation of the Huntress, at least in regards to the title's connection to Batman. Introduced in the Bronze Age, she is the daughter of Earth-2's Batman and Catwoman. Taking on a superhero identity that combined both of her parents' costumes, she was best friends with Power Girl, the Earth-2 counterpart to Supergirl. The Birds of Prey TV show loosely adapted the character, though she was named Helena Kyle and was Batman's illegitimate child.
The mention of cats in the character description could again hint at Ryan's true identity. Batman in the Arrowverse would be old enough to have fathered a child with Selina Kyle, who would herself be old enough to be a crime fighter. The street upbringing and theretofore unknown connection to Bruce Wayne would also make sense if the Helena Kyle version of the character is used. Likewise, Earth-2 Huntress' friendship with Power Girl could be adapted to continue the plot thread of Batwoman's bond with Supergirl.
Carrie Kelley
Introduced in The Dark Knight Returns, Carrie Kelley was a teenager from a distinctly dystopian Dark Knight future. Though she wasn't raised on the streets, her parents barely acknowledged her as she grew up. Saved by Batman when he came out of retirement, she donned a Robin costume and became his new sidekick. In the sequels, she would take the identity of Catgirl in honor of Selina Kyle, before finally becoming Batwoman.
Carrie's idolization of Batman could easily be part of the motivation of the Arrowverse's new Batwoman, especially since the character actually takes that title in the comics. The rest of Ryan Wilder's background doesn't exactly match Carrie's, but her status as an Elseworlds character could be used to make any changes work.
Misfit
Another possibility is that Ryan Wilder is actually Misfit, a relatively forgotten tertiary member of the Batman Family. Misfit, or Charlotte Gage-Radcliffe, appeared in Birds of Prey, created by Gail Simone and Paulo Siqueira. She was a homeless metahuman teen with the ability to teleport, as well as superhuman strength and healing. This allowed her to become quite an adept young vigilante when she debuted as a new version of Batgirl. Informed of the death of Stephanie Brown, but still wanting to be a hero, she renamed herself Misfit, giving herself a somewhat redesigned look.
Misfit's relative obscurity would allow her to be reimagined in whatever way the Batwoman creative team wanted. The character also has the rough background of Ryan Wilder, and her red hair could be compared to Batwoman's wig. In addition, Wilder's relative disregard for the morality of heroics, could be compared to Misfit's flippant attempts at vigilantism, summed up in her catchphrase, "Dark Vengeance!"
While it's possible that Ryan Wilder truly is an original character, the preceding five comics creations all mirror at least some of her known character traits. Even if Ryan is an entirely new character, it's equally possible that elements of these heroines from the comics will be used to mold her.