This was uploaded on my old blog but I deleted that, so here, have them again!
Whilst Selina is not a patient at Arkham Asylum, she is rather good at breaking in. Thus, she will often break in (to the chagrin of Bruce) to see her friends.
As Selina is close friends with Edward Nygma (Riddler), she has also formed a close friendship with Oswald Cobblepot (who is also not a patient). She will go to the Penguin if she is struggling to locate things and in return, as payment, she performs at his club- The Ice Lounge.
When sneaking into Arkham Asylum, Selina will often bring a few stray cats with her as ‘Animal therapy’. Likewise once the rogues escape Arkham they will return their cats, or drop off new strays at Selina’s door. Killer Croc is known to do this the most as cats seem to get trapped in his sewers.
Often Selina will leave a few strays with the inmates- so far three have decided to keep them: Harley, Two Face and Jervis- Harley has an all black one, Jervis’ is grey, and Two Face has a cat that looks like a cow.
Oswald Cobblepot views Edward Nygma as his adoptive son- whether this is due to Eddie’s rough childhood, or Oswald’s loneliness, is unknown.
(Because of events in Hush) Joker is rather fond of The Riddler and keeps an eye out of him (not that he’d ever admit it) because Eddie gave up the name of the crook who killed his wife.
Most patients in the lower levels of Arkham are forced to share cells- like Jervis and Scarecrow, however those on upper levels (like Ivy, Two Face and Joker) get their own cells.
Riddler gets his own room as no one wants to share with him.
During downtime, the inmates are allowed to do what they wish (within reason)- Jervis and Jonathan will often play chess or read, Edward will annoy the shit out of everyone (alternatively he will write short stories and poems), Ivy is allowed in the garden (providing she doesn’t kill anyone), and the orderlies try to get Joker to go to art therapy (he keeps drawing Harley).
The Doctors and Orderlies wear name badges with their job titles written on it, and will rarely say their names near the inmates. Some asked Jonathan Crane (an ex Doctor there) why that was and he replied that it was job protection should the inmates every escape they would know little about those treating them.
(Personal Head canon- doesn’t always stay the same, depends on the fanfic I’m writing) Jonathan Crane looks back on his time as a professor in Gotham University fondly. He remembers his promising student Harleen Quinzel and is proud to see what she’s accomplished as Harley Quinn.
Jonathan Crane and Killer Croc still pronounce words differently as both are originally from the south- other inmates would make fun of them if they weren’t certain Croc would eat them.
Once a month, to keep Jervis happy, Jeremiah Arkham will allow Jervis to hold a tea party- each rogue is assigned a roll: Harley is Alice, Jervis is Hatter, Scarecrow and Riddler are March Hare and Door mouse respectively, Poison Ivy is the Queen of Hearts, Selina will sneak in to be the cheshire cat. These parties are allowed to go on providing no one tries to kill each other.
Bruce Wayne (who part funds the asylum) will often visit the hospital in order to see how everything is running. His appearance however upsets many of the patients. Harley, Two-Face and Eddie know that Bruce Wayne is Batman, though Eddie denies it wholeheartedly- for knowing who the Batman is ruins the puzzle. Croc also knows Bman is Bruce Wayne though this is because of their identical scent.
Mary Louise Dahl (newly incarcerated and an ex girlfriend of Croc’s) will often sneak out of her cell and go to the sewers where the hospital holds Killer Croc. Though the orderlies are aware of this, no one tries to stop her in case Croc tries to eat them.
Mary is the only person, other than Selina, to call Croc his birth name: Waylon.
Not being a natural blonde, Harley will ask Selina to bring her hairdye.
Harley has given everyone in Arkham a nickname. She often goes to see Croc (who puts up with her high pitched nonsense- she calls him Scales)
Harley will also go visit Arnold Wesker and Scarface- they will put on shows for her to make her laugh after fights with Mistah J.
Eddie and Jonathan are huge caffeine addicts- even when they’re in Arkham. Eddie surprisingly likes his black, whilst Jonathan likes his with creamer and sugar.
When the inmates have a mass breakout, they will often congregate in Oswald’s ice lounge- except Zsasz who refuses to go near Cobblepot after that unfortunate gambling experience.
Speaking of Zsasz- he likes to be naked… a lot. Jonathan suspects its so the others can see his tally marks.
Zsasz weirdly loves sweet things (to the point of obsession) and the only ‘Zombie’ Zsasz will happily spend time with is Harley- providing of course she bakes for him.
If she’s good- Harley is allowed in the inmate kitchen where she and Jervis can bake to their heart’s content. They will then sell their creations- Zsasz is their best customer.
Harley and Jervis have a rather popular cooking youtube show, though no one working at the hospital has any idea how its recorded or uploaded. Their recipes are normal enough that any citizen can follow it.
If something big is to happen at Arkham (such as Joker’s party in the game: Arkham Asylum). Eddie will run gleefully around the entire hospital to hide his riddles in the hope of stumping the Batman. He tries to stay a few rooms ahead at all times.
Killer Croc loves monster films- King Kong, Godzilla, etc