Ciaran

Backstory:
He was a very skilled doctor that took care of a small village in the Human Realm, and was the only doctor in the area. After an epidemic hit, he tried his best to treat everyone, until he caught the disease as well.  Wishing to continue treating and helping everyone, he placed a curse upon himself, granting him immortality. However, once the villagers were cured from the epidemic and realized him no longer being human, he was driven out.

A workaholic who cares about his patients’ wellbeing more than his own

He’s generally a nice guy, but appears to be moody most of the time. When he’s annoyed, he is rather snappy, especially towards J. But when he’s in front of his patients, he will immediately flip the switch to be much more patient and gentle mannered.

Although he can’t really stand J’s attitude, they’re roommates (oh my god they were roommates)