Need suggestions about this pinkmeania and Slender-man fic i am going to write

Me and a friend were watching Slender-man videos and one had a cupcake in it and i got this idea for a story about Pinkameana Diane Pie meeting and teaming up with Slender-man

now the basic premise is Diane is banished to earth by Celestia for her violent crimes and she meets Slenderman and they go on a killing spree he catches the victims and she kills them

yes its going to be dark and i need suggestions on how to go about it

like do i make Diane a human or stay as poney when she comes to earth

or how dose she meet Slender man

please help me with suggestions any help will be welcome