All Opinions And Internal Organs Are My Own

We Are Robin - Underground City for a Cult of Homeless People in the subway

Robin War - The tunnel underneath the greenhouse at Gotham Academy that leads to the place the Court of Owl keeps their Talons

Batman and Signal - Signal’s Batcave in Gotham

Gotham Academy - The crawl space that lets you walk between the walls at the Academy

Batgirl (2000) - Cass’ Batcave

No Man’s Land - Poison Ivy’s kids living in Bruce’s tunnels under Robinson Park

No Man’s Land - kids from Tim’s school living in the sewers role playing their DnD characters

No Man’s Land - Alice in Wonderland themed underground railway underneath the museum that goes between Gotham and Bludhaven that’s been abandoned since the 1920s (????)

Detective Comics - um. A “private men’s club” only Killer Croc uses?

Battle for the Cowl - Jason’s pseudo batcave in the train station

Battle for the Cowl - Black Mask’s underground bunker

Batman and Robin Reborn - Dick and Damian’s abandoned subway batcave

Batman and Robin Reborn - like… hidden passageways under Wayne manor that were used to worship Barbatos

Batman Vol 2 - bunker underneath a brownstone in crime alley next to where his parents were shot that Bruce lived in when he first back to Gotham

Batman and the Outsiders Vol 3 - court of owls room hidden in the sewers that Batman kept and keeps random masks and weapons in case he finds a random super powered orphan to help them design their superhero costume

1. Mad Dog

Cain’s first experiment is his adopted son Mad Dog. Cain drove him crazy with his abuse and decided to discard him. One of the guards spared Mad Dog but set him into the wild and basically raised him as an outdoor pet until Nyssa al Ghul convinced Mad Dog to join her League. Cass and Mad Dog have a fight, Cass ends up knocking him out but gets stabbed and dies in the processes and Shiva has to stick her in a Lazarus Pit. What happens to Mad Dog after Cass defeats him is not shown.

Batgirl Vol 1 #71

2. Annalea

Annalea is an assassin for hire also trained by Cain. She’s gets introduced by seducing and killing a man, before Cassandra beats her up and kills her. Apparently Cass is so jealous that Cain loved someone besides her she murders her sister and then tries to force Tim to kill Cain. Thankfully it’s later retconned that Cass turned evil because of brainwashing instead of jealousy, but Annalea’s still dead lol.

Robin Vol 4 #149

3. Marque and the Cain/Deathstroke expiraments

During Batgirl Vol 2 we meet Cass’ older bio sister, Marque. Ever since escaping Cain, Marque has dedicated her life to hunting him down and killing him.

Batgirl Vol 2 #1

Speaking of the evil!Cass arc, Cass meets her while she’s also hunting down Cain, as well as Deathstroke, to get revenge on them for brainwashing her into becoming a killer. Cass learns that Cain has been raising even more girls and also giving them Slade’s super strength serum, training them to take down the meta-hero community.

Batgirl Vol 2 #3

Marque was hunting down these girls and murdering them, giving herself a scar for every “hint of Cain’s blood” she wiped out. Between Marque’s killings and Slade deciding to cut his losses and blow up their base, a majority of them died, but Cain does say there are still some left.

Batgirl Vol 2 #4

Anyways, Cass stops Marque from killing Cain by beating her up in an alley and seriously injuring her, which makes Marque vow that Cassandra is her enemy, not her sister.

Detective Comics #548

Blue Beetle Vol 7 #26

Green Arrow Vol 3 #46, 70

Bruce Wayne: Murderer?

Batgirl Vol 1 #61

Robin Vol 2 #152

Batgirl Vol 1 #26, #72