All chained up(billdip)

Dipper wakes up in a dark room with his twin sister and his grankels chained up in blue chains then bill comes in as a human and he tried to kill dippers grankels which is Stanley and Stanford but dipper stoped bill and made a deal with him and now he has to obey bill to let his grankels and his sister go home safe.
I don't own any of gravity falls it belongs to Alex hirsch