He was imprisoned and tortured in Azmodea for centuries by Noir. He escaped by promising Seth that he would return to free Seth if Seth helped him escape. He betrayed Seth however, by never returning. Shortly after his escape, Nekoda, who had been sent back in time to kill Adarian by the Arelim, finds herself unable to kill such a beaten and weak creature as Adarian was when he escaped.
He was in a prison serving three life sentences in Angola for killing demons who attacked him while he was robbing a bank. His defense of “he was a demon, Your Honor. A crap load of them were trying to kill me and if I hadn’t killed them, they’d have killed me where I stood, then taken over the city and enslaved all you petty and pathetic humans” didn’t sit well with the judge. And they refused to allow an insanity plea since his whole defense was based on: "I am not insane. You pathetic humans have to understand that demons need killing."
Dark-Hunter Timeline VS. The Chronicles of Nick Timeline Edit
In the original Dark-Hunter timeline, Adarian was killed when Nick was eleven during a prison riot. However, after Ambrose changes the timeline in the Chronicles of Nick, Adarian is only wounded in the riot and Adarian kills a prison guard which gets him sentenced to life without parole. So Adarian is still alive when Nick's Malachai powers begin to come in during the start of The Chronicles of Nick.