Part 1

Nightmare and Dream fall into a portal transporting them to a teenager's house. They seem to get attached to the girl . Nightmare and Dream see her as a little sister but Nightmare and Y/N seem to like getting in trouble a lot and Dream is left responsible for their childish behaviors.

When they return back what will the Sanses say to Nightmare and Dream getting along and with a badass little sister .

Will they hide her or face the rath of Y/N getting getting a boyfriend.

Will the trio hide their new found powers as well?