What did he do to deserve such a thing? Or is the onmyoji something that enjoys making creatures miserable?

*tries to remember* Well, Abyssi as a character went through a period of being rather dangerous to humans in Nihon's feudal era because of what they did to his wife (Illumina). So through cunning and subterfuge, he was secretly manipulating the different daimyos to attack one another and creating warfare. The onmyoji, whose name was O-Bou, had Abyssi's young daughter (Tsuki) kidnapped, and so to prevent anything from happening to her, Abyssi took the fall and let O-Bou change him into a comparatively weak human. Thus was O-Bou regarded as a hero.

(An onmyoji is kind of Japanese sorcerer from the Heian period, they supposedly had powers that were based in Shintoism and Taoism. A daimyo is a feudal lord.)

But the intrigue didn't end there, as it was later revealed that Abyssi's jinbu body was still in existence, Abyssi's spirit had simply been torn from it, and O-Bou now meant to animate it himself and secure his own domain, using it as a tool for warfare. The roleplay I ran involved the player rescuing Tsuki from O-Bou, fighting O-Bou, fighting Abyssi's body under O-Bou's control (lol!) and finally allowing human Abyssi close enough to his jinbu body so that he could possess it again and change back into himself.

Afterwards, since Tsuki had been rescued by a human, Abyssi became more peaceful toward them.

I love the low lighting~ verry stunning~ ^^