Nightmare was just sitting there with his tentacles on a nice grassy hill.
And then he saw slenderman using one of his own tentacles to beckon nightmare forward.........

Nightmare's POV (point of view)
I was minding my own business when I see..... a faceless dude? Like he had no face but HE WAS IN MY DOMAIN and he had his own tentacles. It seemed like he was beckoning me forward...?

Author note
Sorry it's short but this is my first book ever and I am super bad at spelling and I know nothing about slenderman lol but feel free to comment and I will try my best to respond to each comment also he is going to fight just slenderman first and then the mystery will come later also none of the art is mine unless stated otherwise.