Scenario 1: Night is a very rich man, he decided to hire Cross as a maid/slave to work in his castle. Basically he has Cross leave behind his normal life and his home to live and work in the castle. Of course we can start at where Cross signs a contract, saying that if something were to happen to him, he couldn't call the police on Night. Dream is actually the one giving him the contract. The next few days Night comes to pick him up while in his passive form, which lures cross into a false sense of safety. When they arrive at the castle Night switches into his other form, basically this a size kink scenario. Cross has punishments when ever he doesn't behave. 

You can choose the punishments and rules.

Scenario 2: NaJ which this ship doesn't exist. Or it's rare.  Cross develops a crush on his hawt teacher. (Sorry i used up all my brain on scenario 1)