Batgirl Cassandra Cain starred in a solo series that lasted 73 issues between 2000 and 2006; in it, original, retired Batgirl Barbara Gordon served as her mentor. That was later followed by a new Batgirl series in which Stephanie Brown, aka Spoiler, took up the mantle from her friend Cassandra (this required some unconvincing hand-waving to get the costume off of Cass and forcing her into story limbo for awhile). In that volume of Batgirl, which lasted 24 issues between 2009 and 2011, original, retired Batgirl Barbara Gordon once again served as the new Batgirl's mentor.
Then, when "The New 52" happened, Gordon returned to the Batgirl role for awhile, starring in a series that lasted 53 issues between 2011 and 2016, and then immediately relaunching for a new volume that lasted another 50 issues, into 2021. By that time, both Cassandra and Stephanie were both reintroduced into the Batman universe, with the latter resuming her Batgirl codename and costume after going by a new one for awhile.
What to do with all these Batgirls? Why not put them all together in a new series, the premise of which would be the obvious one, of the older, original Batgirl Barbara—who had been gradually drifting back towards her pre-New 52 status quo as computer expert and information broker Oracle—serving as the mentor of the two teenage vigilantes?
That was the idea behind the new series Batgirls, which launched in 2022 after a few issue launch of the team-up concept in some back-up stories in the pages of Batman, during writer James Tynion IV's big "Fear State" crossover storyline. As I said, it sounds like a good one, and given the relative success of the three heroines in solo series throughout the 21st century, putting them all on a Birds of Prey-like team together seemed like an obvious move, one that would bring with it three different fandoms.
Oddly, it only lasted 19 issues, fewer than any Batgirl's solo series to date.
What went wrong? I don't know, beyond the obvious fact that it's pretty hard to sell an ongoing comic book series these days.
I was a faithful reader of the original Batgirl series, a big fan of the Cassandra Cain iteration of the character, and an advocate for this very premise for a book, and I wasn't reading it, for a variety of reasons (The New 52 essentially having broken the contract between me as a reader and the DCU as an ongoing setting, comics costing more than $3 a pop now, not reading enough titles to justify journeying to a comic shop each Wednesday any more, etc). I can't speak for the rest of the potential Batgirls readership.
The title had officially been cancelled by the time I got around to reading the first volume of the series, Batgirls Vol. 1: One Way or Another, by the creative team of writers Becky Cloonan and Michael W. Conrad and artist Jorge Corona. Having done so, I suppose I can offer some guesses, the main one of which the title just wasn't very good. Extremely plot-heavy with little attention to character, characterization or ideas, it wasn't really a book about anything more than our heroes fighting some villains, the sort of comic of which there is and has always been dozens and dozens of similar books, many of which offer more than just fight scenes.
(I wonder to what extent the series' launch being tied to "Fear State" might have been a factor. That was a fine storyline by Tynion and company, but it's credibility-straining villains weren't so great as to justify much in the way of tie-ins or the involvement of characters from the extended Bat-family. That said, Bat-events have long been used to introduced new Batman-adjacent titles, including the original Batgirl series, which came in the wake of "No Man's Land".)
After a few short stories in which The Magistrate from "Fear State" are hunting the Batgirls of Batgirl Cassandra Cain and Spoiler Stephanie Brown, who has apparently recently altered her costume so that he has a purple bat on her chest and is also going by "Batgirl" now (Should Stephanie have resumed wearing her own Batgirl costume if she was resuming the Batgirl name...? I don't know; I personally prefer her original Spoiler costume to this more ninja-like, detail-heavy version.), presumably because of doctored footage showing a Batgirl killing someone that was released to them.
This leads to The Magistrate, which you presumably already know all about because you were reading Batman—remember, the series started in the pages of Batman as back-ups, which, again, may or may not have been a factor in the series' failure to catch on—targeting sometimes-Batgirl, sometimes-Oracle Barbara Gordon's clocktower headquarters. At the same time, an anti-Oracle of sorts, known as Seer, targeted Babs, corrupting her information network.
This leads to the two teens having to lie low for a few days, while Barbara sets-up a new status-quo for them and, of course, the new series: The three of them move into a loft together in a new neighborhood, The Hill, and become something similar to a Bagirl-only version of the Birds of Prey, with Stephanie and Cass going out and doing the leg-work of Batgirling, while Babs stays behind-the-scenes, doing the Oracle-ing.
They're immediately set upon by a series of villains, none of whom, I'm afraid, are terribly engaging, which is sort of unfortunate, as Cloonan and Conrad focus on these and their conflict above characterization of the girls and their relationships with one another. (Where were Cass and Steph living before they moved in with Babs? What was their previous status quos? I have no idea; the book offers no clues).
There's the aforementioned Seer, who can hack his or her way into Oracles networks, and seems to have an unexplained grudge against Babs and the Batgirls. There's Tutor, a prolific spray-paint artist with an anti-society bent and some sort of mind-control abilities that turn victims into mindless zombies that due his bidding. There's Tutor's patron, the latest villain to go by the name Spellbinder (the third, by my count). And there's The Saints, former, radicalized members of The Magistrate who resemble cartoonier versions of Peacekeeper-01 (you did read "Fear State", right?) and are each named after a saint, Tarsus, Valentine and Assisi. And there's the Hill Ripper, an unknown, unseen serial killer who seems to be stalking the girls' new turf, though they don't come into direct contact with him or her this volume, despite Steph suspecting a neighbor, based on some Rear Window-esque suspicions.
If that seems like a lot of moving pieces for the first six issues of a new series, it's mostly just Tutor and Spellbinder who are involved. Seer makes an attack and some taunts, but is mainly a background player until they're surprise appearance at the cliff-hanging ending, and the Saints, seemingly manipulated by Seer, attack a couple of times, but they aren't the focus of the storyline either.
It's all...fine, but it's also light on substance, and what I'd expect from the series, with, as I said, no real focus on the characters or their relationships with one another.
The art by Corona is pretty great, and it's hard to imagine fans being turned off by it. His Cass highlights her visual characteristics, of being something of a creepy cross between Batman and Spider-Man, in a tight, little, slightly feminine package (there's one great splash panel, near the climax, where her arms blend into her cape, giving he appearance of a monstrous bat). The other two Batgirls are less visually interesting in conception, but nevertheless well-rendered, as are all three characters when they are out of costume.
I'm curious about what went wrong with the tile, exactly, and interested enough in the characters to follow the rest of the series in trade, but, with only the first third to go on, I would guess the low-calorie approach to comic book storytelling didn't retain enough eyeballs on the book to make it as successful as any of the girls' solo outings to date.