Martin Joseph was the Warden of Blackgate Prison.
Although the warden of Blackgate Prison, he was largely more concerned of the political role of his job as Warden instead of his main duties, which resulted in it being a hotbed for criminals and corrupt cops, and the prison falling into a dangerous amount of disrepair, although he himself was not corrupt. On Christmas Eve of Batman's second year, Joseph, largely due to pressure by Commissioner Gillian B. Loeb for political purposes, had Intern Harleen Quinzel do a re-evaluation on the serial killer Julian Gregory Day under the pretense that he was a manipulator. However, the same evening that Day was to be executed, he was attacked by Black Mask's (actually the Joker's) Henchmen in order to get access into the prison. After Black Mask threatened Joseph's family and burned his left eye out with a lit cigarette, Joseph let Black Mask and his henchmen into the prison.
One of Black Mask's Henchmen tried to kill Joseph with a Baseball Bat in order to tie up loose ends (he also assured him that they hoped that Black Mask kept his word that regarded leaving his family alone), but Joseph was saved by Batman just in the nick of time, and Joseph initially attacked Batman with a Pipe out of panic. Because of his forced role in the ensuing riot, Joseph underwent an internal investigation with pressed charges against him. After the Joker was incarcerated and managed to start another riot, Joseph was taken hostage by Joker, but was freed by Captain Gordon while Batman was forced into a fight to the death with Bane by the Joker and also attempted to aid Gordon in releasing Joker from the electric chair only to be knocked out by the mass-murdering psychopath while he restrained Gordon.
After Batman managed to "kill" Bane by placing him into Cardiopulminory Arrest, Joseph stood up to the Joker and demanded that he put the gun down. Unfortunately, the Joker, after he decided to put Joseph down instead, tried to shoot him and Gordon intercepted the bullet. Joseph then expressed relief that Gordon still had his bulletproof vest on when he saw that Gordon had survived, and went alongside him to pursue the Joker while Batman resusicated Bane. However, shortly after Batman beat Bane (the latter of whom had injected himself with TN-1 out of desperation), Joseph ended up shot by a sniper in Death Row with a Medevac that was dispatched for him. Gordon managed to stop the sniper and also grazed Killer Croc's shoulder in the process. He then told Batman that Joker was headed for the Prison Chapel.
Three months and a half months later, Joseph was taken hostage during a third riot that broke out at Blackgate and was ambushed by the Joker due to the latter who deduced the secret exit in his office to the sewers and ambushed him there. Joseph then ended up wired to several explosives by the Joker, as well as rigged the doors to set off the bombs if opened, with Joker, who also made sure that the control boxes that activated the explosives caused the bombs to activate if they were cut off the wrong way. Batman later saved Joseph, who then left to assist his staff and vowed not to let Black Mask or anyone else kill any more of his personnel.
- Harleen Quinzel: You wanted to see me, Warden?
- Warden Joseph: Yes. I need you to re-evaluate Julian Day.
- Harleen Quinzel: Oh. Didn't you see? I turned in my evaluation last week.
- Warden Joseph: I saw it. And I need you to do it again.
- Harleen Quinzel: I'm not sure that
- Warden Joseph: You have to understand, Day is a manipulator - a very experienced one, and you, well, you're still in your residency.
- Harleen Quinzel: I don't see anyone doubting that Mr. Day is insane and should be tried as such. I'm actually considering writing a paper about him.
- Warden Joseph: Miss Quinzel, I'm giving you a chance here. Do you know what happens if the prosecution can try Day as a sane man?
- Harleen Quinzel: He'll get the death penalty.
- Warden Joseph: And this city will thank you for helping to remove a cold blooded killer from its streets.
- Harleen Quinzel: So, we're not here to help rehabilitate the sick?
- Warden Joseph: Heh. This is a prison, Miss Quinzel. Not a mental health clinic. If you want to see a successful end to your residency, I suggest you keep that in mind - and re-evaluate Julian Day.
- Harleen Quinzel: I see. Perhaps... perhaps I was a bit hasty with my evaluation.
- Warden Joseph: Excellent. I'm glad that we could
- Harleen Quinzel: In fact, I think it would be excellent experience if I was the first to give all new inmates psychological evaluations.
- Warden Joseph: You're not a doctor yet. That's not your
- Harleen Quinzel: Like you said - I need more experience with these... manipulators. Perhaps more exposure to these types of criminals will help me learn to tell the difference between the fakers and the truly insane.
- Warden Joseph: Why would you want to spend any more time with these freaks than you have to?
- Harleen Quinzel: The criminal mind is a fascinating subject for a research paper... or a book.
- Warden Joseph: Pff. It's no skin off my back. Knock yourself out.
- Judge Harkness: A killer is a killer is a killer. You think it matters to the victim or their families if he claims that he's insane? No. I'm not making special exceptions for all of these... freaks that seem to be popping up. This one was trying to play the system just like the rest of them. Feigned insanity is no defense in my courtroom.
- Warden Joseph: You don't think it's a little... blatant? I mean, with his obsession for the holidays.
- Judge Harkness: In this city? They'll love it. Poetic justice, I say.
- Warden Joseph: Alright. Well, Christmas Eve it is then.
- Judge Harkness: Excellent. I'm throwing a little Christmas party that night - we're going to watch the execution from my home. You should come by, bring your wife. Pick up your gift.
- Warden Joseph: I'll do that. And make sure you have something for my wife too. She likes diamonds.
- Judge Harkness: Hmph. And they told me you were soft.
Despite the fact that it was revealed in Arkham Origins that it was actually the Joker, who was disguised as Black Mask, who burnt out his left eye, Joseph still believed that it was the latter during the events of Arkham Origins: Blackgate. That was most likely set in place by the game developers to avoid spoilers for players who may played the handheld installment without having played Arkham Origins, as both games were released simultaneously and marketed as containing no significant plot points that would spoil the events of the other game (the Joker's reveal as Black Mask's impostor served as the turning point of Arkham Origins).