WARNING: The following contains spoilers for "Batgirls," a story in Future State: The Next Batman #2, by Vita Ayala, Aneke, Trish Mulvihill, and Becca Carey, on sale now.
The Future State timeline is a dark reality where everything is different from the main DC Universe. Most of the old superheroes have gone through devastating and life-altering ordeals, and many of them have been replaced by young counterparts, both new and familiar to DC readers. In Gotham City, the situation has grown dire. The city is now policed by the Magistrate, a military-like force that is hunting down every remaining masked superhero. As we have discovered in multiple titles, this has essentially spelled doom for the Bat-family: Batman is believed dead, Barbara Gordon is missing, Tim Drake is on his own and there is also another new Batman perched atop Gotham's skyscrapers.
As for Cassandra Cain and Stephanie Brown, who both suited up as Batgirls at the end of the Joker War event, "Batgirls "reveals that they are both imprisoned. And throughout all the darkness of this new reality, Stephanie is able to prove herself the most devoted member of the entire Bat-Family.
When Cassandra Cain is taken to the Magistrate Detention Facility, she is placed in the same cell as fellow Batgirl, Stephanie Brown. But when the two are reunited, it's clear that they have had a falling out. Cassandra is furious at Stephanie, who is acting uncharacteristically aggressive. And that is for a very good reason: as we come to understand it, Stephanie is pretty much the big boss inside the prison. She's now made friends with plenty of villains, and she basically runs the place. What's more, she's needlessly defiant to Cassandra -- confrontational, even.
The reason Cassandra is so angry with her is that Stephanie betrayed the Bat-Family when the Magistrate rose to power. Indeed, it's revealed that Stephanie turned her back on the team, and had a public falling out with Nightwing. They all consider her a traitor, especially after she started working with villains. But, eventually, she was caught and locked up in the Magistrate Detention Center.
In prison, Stephanie keeps up the confrontation between her and Cassandra going for a while -- that is until the two are eventually locked up in solitary opposite one another. At that point, with the two of them all alone, Stephanie explains that she has been on an undercover mission all this time to find Barbara Gordon. The only one who knows about it is Dick Grayson, and he agreed to let her go work for the other side so they could find out more information about her whereabouts.
During all this time, Cassandra worked with the bad guys while all of her friends believed her to be a traitor. And she tolerated it all if it meant she could find Barbara Gordon, her mentor. It's a dark path for the character, but it also allows her to show that she is the Bat-family's most dedicated member. It doesn't matter to her that everyone now hates her -- what is most important is finding Batgirl. At least Cassandra finally knows the truth, which means she understands what Stephanie has been through all this time, and how she suffered through all of it alone. But now, Stephanie is no longer alone. Now, she's with Cassandra again, and the Batgirls are ready to fight back.