When Jeremiah was a teenager he walked into a corner store being held up at gun point by an escaped inmate of the nearby Arkham Asylum, which was coincidentally run by his uncle. The gunman had already killed the store owners, but when he went to shoot him, Jeremiah seemed to know all about the gunman's hurt and past and talked the gunman out of shooting him. The gunman then proceeded to commit suicide and Jeremiah knew he would be destined to succeed his uncle as the head of Arkham Asylum. This destiny came true after Jeremiah's uncle Amadeus Arkham died after going insane.Jeremiah proceeded to demolish the asylum before rebuilding it with state of the art systems to keep Arkham's criminals, such as The Joker, The Scarecrow and Cornelius Stirk, contained.
Jeremiah Arkham first appeared in and had his his longest and most significant appearance in the story arc "The Last Arkham" which was the first story arc of Batman: Shadow of the Bat. In this series Jeremiah is portrayed as the somewhat sadistic administrator of Arkham Asylum who has delusions that the criminals he houses could one day be housed in society.
Jeremiah, would appear as a minor character through out several of the Batman titles always beliveing that the inmates of Arkham could be cured. This would change in the Batman: Life After Death, when it is revealed that Jeremiah had been the Black Mask and was using the inmates to build his criminal empire. He was stopped by Batman and put into his own asylum.
After Flashpoint, the DC Universe changed, and Jeremiah was once again in charge of Arkham Asylum. He had never become the Black Mask, although it's hinted at that he did wear the mask. He still believes all the inmates can be reformed and that the Batman should be in the Asylum.
Major Story Arcs
The Last Arkham
For more information see: The Last Arkham
Soon after the new Arkham is built, Batman stumbles across a series of murders resembling Zsasz's MO. Zsasz had been an inmate at Arkham Asylum for a long period, but the similarity was too much to ignore, so Batman fakes insanity to get into the asylum to investigate. However, Jeremiah is unknowing of this plot and takes Batman's insanity as genuine. Zsasz had actually been the murderer and had been getting out of Arkham by a series of underground tunnels put in place by the contractor on the asylum's revamp. Zsasz, upon hearing of Batman's arrival, predicts it's a set up and begins to plant seeds of doubt and hatred towards Batman in Jeremiah Arkham's mind. In addition to this, Jeremiah blames Batman for stopping his inmate's rehabilitation. The situation erupts when Jeremiah locks Batman in a room and sets the inmates of Arkham on him, including Amygdala, The Riddler and others.
After the storyline is wrapped up, and Zsasz uncovered, Batman questions whether Jeremiah is himself mad. Jeremiah denies it, but in the closing scene of the comic, he asks himself whether he will end up like his insane uncle and whether he is indeed mad as Batman suggested.
No Man's Land
For more information see: No Man's Land
During the events of No Man's land, Jeremiah was seen in the wreckage of Arkham Asylum gathering up the more benign inmates of the asylum and making plans for turning the hospital into a sanctuary for the ill.
Life after death
For more information see: Life After Death
Jeremiah's sanity was not what it seemed. Taking up the mantle of the Black Mask, Jeremiah took over the criminal underworld. He planted chips in several Arkham inmates, which would detonate if they did not work with him. With Fright, Hugo Strange, and Doctor Death, Jeremiah resurrected the Reaper to distract Batman. When Jeremiah combated Batman (Dick Grayson), he used a gun with rubber bullets. In the beginning, Dr. Arkham told Batman (Dick Grayson) that he would use rubber bullets, even if his life was at stake. He didn't like to kill people, however the Black Mask inside of him did. Eventually Batman tracked him down (due to his poor thinking skills), and captured him. Jeremiah was unmasked and is currently locked up in his own Arkham Asylum.
The Night of the Owls
For more information see; The Night of the Owls
The Court of Owls has ordered the death of Jeremiah and send a group of Talons to kill him. Batman shows up but is no match for the Talon's numbers, so Jeremiah makes a deal with Black Mask and releases him and the other inmates on the Talons. When Batman stops the Talons on his own he knocks Jeremiah out and takes him to his safe house til the Night of the Owls is over.