Perhaps having Lady Bone Demon, a dangerous spirit wander all around the city wasn't a... Good thing. And well, MK and his small gang and his mentors; Wukong and Macaque still couldn't defeat that witch. So... They had to ask someone more experienced.
You all decided to make a truce for now, you help them defeating Lady Bone Demon. And they'll let you steal something NOT theirs, but of someone else. You agreed. Despite you being a villain, the gang have seemed to start trust you rather quickly. Maybe they have wanted you as an ally before? Hard to say.
Anyways... You all were into Lady Bone Demon's palace. She was on the verge of getting defeated and as you were about to give the final blow. You suddenly stopped and threw a spell towards the gang, imprisoning them into a cage of thunders.
The gang remained shocked and betrayed. As Wukong and Macaque tried to break the cage, but nothing, the thunders-like-barrs would just burn their hands. MK's eyes widened up and took a small step forward until his body barely touched the barrs.
MK : "you... Youโ you betrayed us!"
Wukong : "we trusted you! How could you!?"
Macaque : "I knew it... You never change."