While you are digging into batfam lore, could you perhaps help explain what the batkids' legal names all are? Fanfiction has messed me all up. Did any of them actually legally take Wayne as their last name? I see it most often with Tim (i.e. Timothy Drake-Wayne) and Cass (i.e. Cassandra Wayne) but I haven't read any comics that I recall that actually called them that.
Sure! A quick rundown of who's actually part of the Wayne family:
Wayne family: Dick, Jason, Tim, and Cass were all legally adopted at one point or another in the post-Crisis universe (post-reboot is....complicated. Dick, Jason, and Tim are all once again adopted after a long series of retcons; Cass's status is still unknown). Damian is Bruce's biological son.
NOT Wayne family: Babs, Steph, any members of the Fox family (Luke, Tam, Tiffany, Jace, etc), Harper Row, etc.
Duke is a complicated case; he was Bruce's temporary foster son for a year before moving in with his Uncle Jay, where he now lives. He's...sort of considered Wayne family, in that at least Jason and Tim consider him to be sort of their brother, but he wasn't adopted and no longer lives with Bruce.
Other:Ā Kate and Bette Kane, who are Bruce's cousins and part of the Kane family.
As for legal last names and who actually calls themselves Waynes:
Damian's legal last name is Wayne. The al Ghuls tend to call him "Damian al Ghul" when he's with them, but legally his last name is Wayne; it's also the name Damian goes by UNLESS he's specifically attempting to leverage the al Ghul name amongst his family or the League of Assassins.
Dick continues to go by and think of himself as "Richard John Grayson" even after being adopted, though he explicitly calls himself Bruce's adopted son in several arcs after his adoption happens. You can take your pick of reasons why this might be (and there's quite a few to choose from, mostly connected to Dick's love for his bio parents and already being an established adult when Bruce adopted him), but Grayson was and remains his legal last name.
Jason canonically remained "Jason Peter Todd" after his adoption, per his death certificate:
Jason's death certificate, naming him as "Jason Peter Todd." -Batman Annual #25 (2006)
He was also "Jason Todd" to the general public; it's what people call him when they talk about him both before and after his death. The Red Hood and the Outlaws Rebirth comic (specifically RHATO #33) confirms that this is the case in the post-Flashpoint universe as well. However, there's a pretty reasonable canon foundation to assume that had Jason's adoption not happened in the 80s and had writers not wanted to complicate things, he probably would have chosen to hyphenate and become Jason Todd-Wayne, based largely on a) Jason's relationship with Willis Todd and b) Bruce and Jason's relationship before his death.
We simply don't know what Cass did. Cass was adopted off-panel in the vague period in betweenĀ Batman RIPĀ andĀ Final Crisis, but Bruce's death threw everything up into the air; Cass was then promptly put on a bus and shipped out to Hong Kong for the duration of the Reborn era, and since she shows up in a grand total of 8 comics during that time we just don't get enough information to make a judgement call about her last name. Her two appearances in Tim's Red Robin book still call her Cassandra Cain, but it's unclear whether Fabian Nicieza, the writer, even knew her adoption had happened:
"Cassandra Cain, former Batgirl, remains one of the most dangerous fighters on the planet..." /// "Cassandra Cain, aka The Black Bat, Hong Kong operative for Batman, Inc." -Red Robin #17 & #25
Since Cass never had much of a public identity to speak of in the first place (and for a long time didn't even want one), it's super ambiguous what her legal status is and what last name she holds post-adoption. It's pretty reasonable to assume she becomes Cassandra Wayne, though, and it's also my personal preference. Though her relationship with David Cain is complicated, she doesn't hold much attachment to him as a father; likewise, there's really no reason for her not to take on the Wayne name given her attachment to Bruce.
Tim is the complicated one here, mostly because his adoption was such A Productionā¢. Tim was formally adopted about a year in-universe after the events ofĀ Identity Crisis (when Timās dad was killed by Captain Boomerang). The adoption was pretty high-profile; Tim and Bruce even sat for an interview about it:
From 2007-2011, he's called Tim Drake and Tim Wayne (and occasionally Tim Drake-Wayne) pretty interchangably depending on the writer and situation. His legal name is probably Tim Drake-Wayne, though it's actually ambiguous. He tends to go by Tim Wayne in public while usually referring to himself as Tim Drake in private:
"And by the way, it's Wayne when I want a favor or a table at Bartese, and it's Drake when I look in the mirror." -Red Robin #15
"A question for Mr. Wayne--" /// "Reporting live from the reopening of the Newton Community Gym where Tim Wayne is about to address the crowd." -Red Robin #14 and 15
Post-Flashpoint, that adoption was erased and Bruce and Timās relationship was very strained; in the Rebirth era, his adoption was implied to be canon again in both TynionāsĀ Detective ComicsĀ run and King's Batman run, but we didnāt get confirmation until Infinite Frontier andĀ Urban Legends, where Tim is once again explicitly adopted and occasionally called Tim Wayne, though he still mostly goes by and is referred to as Tim Drake:
"But just to be clear--we're not splitting the bill, Tim Wayne." -Urban Legends #4
"...and then Mr. Wayne just adopted you? Awful generous of him." -Urban Legends #4
Tim is also the only one regularly referred to in public as "Bruce's adopted son." Most of the time they're referred to as "Bruce Wayne's wards," so whether the adoptionsĀ are public knowledge or not is questionable, but their status as his wards and foster kids is not. Though they largely never lived in the Manor at the same time, they've all attended various public functions as Bruce's kids and acted on Bruce's behalf in various capacities while in the public eye.
tl;dr Tim is canonically the only one who takes the last name "Wayne" upon being adopted; he generally continues to refer to himself as Tim Drake, but canon calls him "Tim Drake," "Tim Drake-Wayne," and "Tim Wayne" pretty interchangably afterwards. Dick doesn't change his name and canonically Jason didn't either, though you could make a case that he might have hyphenated had his adoption been written in the modern era. We don't see Cass enough after her adoption to know either way; however, her existing canon relationships with Bruce and her biological family heavily support and/or imply that she probably became Cassandra Wayne.
