Cassandra Cain has been a valued member of the Bat-Family for years. Despite her horrific upbringing, Cassandra has proven herself a true hero and ally to the Dark Knight. Only a true disaster like "No Man's Land" could have forged Cassandra into one of Batman's most heroic allies.
Cassandra first appeared in Batman #567 by Kelley Puckett and Damion Scott. When she was introduced, Cassandra was one of Barbara Gordon's couriers, going on recon missions throughout Gotham. During "No Man's Land," Oracle taught Cassandra how to read and speak English, as everyone presumed that she spoke a different language. Cassandra later stepped in to save Commissioner Gordon from an assassination attempt, also identifying the culprit.
David Cain was hired by Two-Face to kill Gordon. When Cain came back for more, Cassandra continued to protect both the commissioner and Oracle. Cassandra tackled Cain through a window, saved from the fall by Batman. After saving her, the Caped Crusader learned the truth about Cassandra: she was David Cain's daughter. Cain didn't teach Cassandra any real language, only communication through violence. Hearing that Batman was having difficulty with Two-Face, Cassandra put on a mask and went after the former DA. While Batman took down Cain, Cassandra captured Two-Face, as the Dark Knight couldn't be in two places at once. Appreciating Cassandra's efforts, Barbara gifted her with an old picture of herself as Batgirl. Cassandra's help also inspired Batman to finally call on his allies during "No Man's Land."
In Batman: Legends of the Dark Knight #120 by Greg Rucka and Mike Deodato, Jr., the Caped Crusader fired the Huntress from her role as Batgirl. Immediately after, Batman gave Cassandra the mantle of Batgirl, with Barbara's blessing. Nearly all of Batman's allies were skeptical of Cassandra at first, given her heritage. Yet the Dark Knight and Oracle both vouched for the new Batgirl, insisting that she could be trusted. Cassandra's first mission paired her with Azrael, in Azrael: Agent of the Bat #56 by Dennis O'Neil and Roger Robinson. The crime-fighting duo was tasked to uncover and stop the activities of Nicholas Scratch, who was responsible for Gotham being declared a no man's land. While Batgirl defeated all of Scratch's henchmen, Azrael publicly defeated and humiliated Scratch in combat.
Cassandra also worked with Azrael to evacuate Gothamites from the Joker's territory, narrowly avoiding an encounter with the Clown Prince of Crime. In Batman #569 by Janet Harvey and Sergio Cariello, Cassandra got her first solo mission. Eager to earn her place as Batgirl, Cassandra volunteered to defend a petrol station and its owner from a group of criminals. Cassandra saved the owner and the gas, succeeding in her assignment and making Batman proud.
The events of "No Man's Land" certainly earned Cassandra her place among the Bat-Family. Forming new partnerships and succeeding in several missions, the new Batgirl became a big part of Batman's inner circle. Cassandra's place became evident during "Bruce Wayne: Murderer," as she was the first crime-fighter to arrive at Wayne Manor after Vesper Fairchild's murder. During "Bruce Wayne: Fugitive," Cassandra was the one to figure out that a specific nerve strike was used on Vesper, revealing that Bruce had been framed for her murder by a professional. Working with Nightwing, Batgirl recreated the crime scene to definitively prove that Bruce was framed. When the killer was revealed as Cassandra's father, David, Cassandra convinced Cain to turn himself in to the authorities after he was beaten.
Since then, Cassandra has gone from Batgirl to Orphan, remaining an active part of the Bat-Family. Orphan maintains strong relationships with other Batgirls, including Stephanie Brown and Barbara Gordon. Cassandra has also fought on several of Batman's teams, including the Gotham Knights and the Outsiders. If not for "No Man's Land," Cassandra Cain wouldn't have entered Batman's world, let alone the Bat-Family.