Sunday Sinner (Satania x Reader, Lemon)

Satanichia

You are an average student at your class. You get average grades and have average athletic ability. Well you're below average since you don't have any friends. You have science class today at yor school and are told to break into groups of two. You look around concerned since you don't have any friends in this class. And in hindsight you don't think you've ever even had a conversation in this class with anyone now that you think about it.
"Nooooooooo!"
You snap your head to the source of the sound and look upon a girl with red hair and a bat hair clip talking to a girl with white hair.
"You don't want to do the project together?" The white haired girl says in a calm, almost angelic voice.
"of course not! I have the feeling you'll disect me!" The red haired girl yells back.
But the project is on darwinism. You think to yourself but don't say.
"But who are you going to do the project with?" The white haired girl says in a playful voice.
The red haired girl looks around trying to find a partner before stopping and staring at you. You look away worried what she might think if some random guy was listening into a conversation that didn't concern him. Second later you feel a slam on your shoulder.
"YIP!" You yell
"This is my partner!" You turn to see the red haired girl behind you with her hand on your shoulder.
"Oooh excellent choice Satania-san" the white haired girl says.
"I'm not plaything you know..." You object though no one seems to have heard you.
"Now then." The red haired girl turns to you with a smug smile. "It's your lucky day human! I. Satanichia McDowell Kurumizawa have decided to answer your pathetic prayers and allow you to serve under me in this project" she says with a big satisfied smile.
"Oh uh... please take care of me" you respond
"Of course!"
The rest of the day you work on your project with her. Or rather you do the work as she watches since Satania is... well.
"Snakes are descendents from lucifer since he was proud of his form and felt it was a crime to keep it to himself! Fish actually could always breath just look at dolphins! Snails were actually intended to rule the earth but you humans proved more resourceful so god gave up on em, for now."
Is insane.
After a long day the teacher announces he will grade them on Monday and if students wish to finish them over the weekend they can.
"Sigh. Goodbye my weekend." You mutter to yourself.
You turn to the corner and see your partner gloating to the white haired girl, a blonde messy haired girl, and some third one.
"Our project will be the best in class! You will grovel at it Gabriel!" Satania exclaims.
"I bet" the messy haired girl responded.
You sigh and get up. Satania notices
"Ah my servant! Before I dismiss you you mat give me a report!"
"A report?" You say confused "uh well I'll have to finish it over the weekend and since your not helping I'm thinking about just taking your name off of it" I respond nonchalantly
"GEH!" Satania jumps.
"N-now now let's not be rash. Ummm. Oh! You can come over to my domain over the weekend. Were we will finish the project as master and servant." Satania responds.
You stare blankly at her. She stares back now sweating.
"I-I'll prepare snacks!"
"I'll be there."