You were the minion of the Lady Bone Demon, simple as that. Were you controlled to do this? Who knows. Were you doing this out of free will? Maybe. Were you forced into it? Perhaps. However you became the Lady Bone Demon's minion wasn't relevant anymore.

You had gotten into a bit of trouble with MK, his friends, but most importantly, Sun Wukong. You had been causing WAY too much trouble for them-rewinding all the work in their plans, setting traps, and even stealing the map to the Samadhi Fire. So after a bit of careful planning, the group kidnapped you and had you tied up. For interrogation, of course.

"Alright, you brat." Wukong crossed his arms, pissed. MK puffed up his cheeks, as if trying to be intimidating. "Tell us why you're working for the Lady Bone Demon! ...or something."