Adrian Chen

Dr. Adrian Chen was one of the many doctors present during the Joker's takeover of Arkham Asylum.

Before Arkham Aslyum Incident
When Arkham Asylum was reopened by Quincy Sharp, Dr. Chen started working there as psychiatrist, and treated the criminally insane patients of the asylum.

Arkham Asylum Incident
When the Blackgate inmates took over the Medical Facility, Dr. Chen was in the Surgery Room. The inmates had strapped Chen into a chair and tortured him to set him as bait. Batman then appeared and Dr. Chen told him it was a trap, to which Batman replied: "I know, just not for me", before he beat all the thugs and released him. Chen then went and sat into a chair, and thanked Batman.

If Batman returned to see Chen in the Surgery Room, he's not there. Presumably, he went and found a place to hide out the remainder of the Joker's riot. Alternatively, he could have found a way off of Arkham Island, though that was unlikely.

After Arkham Asylum
If Chen survived the Joker's takeover, it was likely that he went back to his usual duties as an Arkham doctor until the asylum was closed down by Mayor Sharp.

Quotes

 * "Batman!" 


 * "But, it's a trap!" 


 * "I think I will be OK, thank you for stopping them."


 * "They tortured me, set me as bait!"

Trivia

 * Despite Dr. Chen being rescued together with Dr. Kellerman and Dr. Cassidy, he did not join them in hiding from the inmates.
 * Dr. Chen was the only doctor at Arkham Asylum (that the player knew the name of) who did not have any known patients. Dr. Whistler was known to treat Victor Zsasz (after he was transferred from Dr. Cassidy) and Killer Croc. Dr. Kellerman was confirmed to have treated Scarecrow and Poison Ivy. Dr. Cassidy treated Zsasz (before she transferred him to Dr. Whistler) and Great White Shark. Dr. Young treated the Joker and the Riddler (among others). Who Dr. Chen's patients were, remained unknown.