Xing and ling is the duo sibling of the witch of puppets. If one of them offered you something good or bad. Their turn you into one of they're collections of puppet. And your jobs is to avoid them or else you will end up being they're puppets forever and if you become one of they puppets. Your jobs is to kill or drag the human's to them. That's your jobs to do. Xing is a girl and Ling is a boy. Both of them are twins but being the duo sibling rivalry of the witch controlled.