Moon light Nightmare x Reader (COMPLETED)

chapter 10: First mission

You run to what seems to be a courtyard. You skid out the door way and start climbing a tree. You settle on a branch and you hear a rustle next to you. You look down at your hands as you wrap your legs around the branch tightly.
"Are you alright my princess?" Nightmare asks from beside you.
"I-I don't know why I did that….. it's not like me….." you say as tears fall down your face. The drops fall from your chin onto your hands and you feel Nightmare give you a tight hug.
"It's okay. You didn't hurt the idiot. Everyone was surprised though. You gained respect though."
"I don't want to gain respect if it means hurting others though! That's not right!" You say as you cry harder. You pull away from him and try to climb up higher but slip. You let out a small scream but never hit the ground. Your eyes open and you see a cyan aura around you. You look up and see Nightmare with his eye flaming and an aura around his hand. He sets you on the ground and you see the others watching you. You pull on your button up on your shoulders before you clutch the shirt together at the collar. Nightmare appears beside you and picks you up.
"Anyone who does that to her again will get dusted. You're lucky she put you in your place instead of me." He growls before walking away with you. You see Cross following behind you.
A week later you throw on a gray t-shirt, black ripped jeans and a sleeveless hoodie. You pull on a set of black leather combat boots. Sighing you go out of your room. It's been awhile since you've talked to the real Nightmare. It irritated you. Your aura was telling the others to stay away. 
"You seem to be in a bad mood, ready for lessons?"
You look to Cross before scowling at your friend. He looked surprised and you sigh. "Sorry, just in a bad mood."
"Well, Senpai says that you can come with us today."
"On the mission?"
"Yeah. You have to stay close to me and Senpai but you'll get to see what we do. You might not like what you see though."
"When are we leaving?"
"Two hours."
"Let's get ready then." Cross walks to the throne room with you and takes his place. You walk up the pedestal and sit in the arm of the throne. You see everyone else there. Nightmare puts an arm around your waist.
"Nice to see you brought her with you Cross. And in perfect condition too. You're in a better mood Princess, that pleases me. I knew bringing you along would be a good idea. Now to the mission." Nightmare debriefs the AU that they're going on their mission in. It was called Storyshift. The roles were much different. You were intrigued. Nightmare made it clear, no dawdling. In, out, no stalling. While he's talking you decide to contact (Y/N).
"Guys, got a situation." You say to her "They're attacking in full force. They're attacking Storyshift."
"Are you with them?"
"Yes."
"Is everything clear?" 
"Yes sir!" Everyone says. Nightmare stands up and you take his arm.
"Stay close. Me and Cross will protect you." 
"He already mentioned. Nightmare, I know there's still good in you." He sighs and looks at you.
"You overestimate me. Let's go." He walks down the pedestal with you and opens a portal at the doorway. One by one the others go through. Cross goes through then you and finally Nightmare. You were in Snowdin forest.
"Snowdin?" You ask. Error teleports off somewhere saying that he'll be back.
"Yeah. This is Snowdin. We start here." Killer says him Dust and Axe run off and you go forward with Cross and Nightmare.
"The judge here is annoying. Stay close to Cross, I'm going ahead." Nightmare says and you watch as he melts into darkness.
"I'll protect you here. Come here." He holds out a hand to you and summons his knife in the other. 
"I don't need protection. I have my spells." You cast a shield spell to make sure only those that you trust can get within 5 feet of you. Cross does his job as you watch sadly. Soon you come to Snowdin village. You go sit by the sign and watch most of the town get slaughtered when suddenly Blue bones get fired. You hear a Gaster blaster charge and fire so you duck to the ground. You look to see Ink and Blueberry. They start fighting, you see Error and Axe fighting Blue while Nightmare and Cross fight Ink. Dust and Killer had decided to finish up the forest and ruins without you.
Soon though you're tackled into a hug by (Y/N). You look over at her and give her a small smile then sob softly. She was dressed in training clothing, black and reds. You were so confused, how could the one you love and your best friend do this?
"DREAM!" You hear Nightmare roar. Both of you flinch at his loud voice full of hatred. Looking over you see the two brothers deep in battle. 
"I don't want to fight you Brother!" Dream yells back. You both can't stop watching the fighting. You had tears rolling down your face.
"This….. I-I don't know what to-" 
"It's fine. You don't need to say anything. " (Y/N) cuts you off. "I know your man is still not 100%. I can see it how he's moving."
"I don't consider that darkness the one I love…." You whisper out. She looks over shocked but you're watching the two brothers fight. "How are you so calm?"
"I…. there's a lot that I've had to do or have seen…. I'm from Underfell…. shit ain't always pretty there-" a stray blast from gaster blaster shoots at you and she pushes the two of you out of the way. She hissed in pain as it grazed the back of her leg.
"Oh my gosh! You're hurt!"
"Focus on the battle. How good of an actor are you?"
"Pretty good. Why?"
"Idea time~" she sings out. You look over to her and she tells her plan to you and you look back and nod. You use your magic to let the Star Sanses know that you have a plan but don't explain what it is. "HEY!" She yells as she pins you to the ground and pulls your head back. She takes out a knife and holds it to your throat. "I want you out or the girl may not survive."
A silence settles over everyone. Her friends all look horrified. 
"You. You let her go!" Cross yells. She presses the knife against your throat more.
"No. You leave this AU. Now. And if you do I may consider letting her go." She states. She stares Nightmare right in his one visible eye and he growls.
"Axe, Error, Cross. Go get Dust and Killer. Then go home." He says and she clicks her tongue. 
"See Nights, you gotta go too. The girl will be brought back to her home by Ink afterwards." He starts getting mad. "Don't think I wont hurt her. I'm from Underfell. You don't know what I've had to do to survive." Your eyes were pleading as you stare at him. He frowns but follows the others through the portal. She sighs and lets you go once they are. 
"I know you were just acting but…."
"(N/N), as I said, I'm from Fell. Lots of acting needed." you nod and you all start helping those who were hurt.
"(Y/N) what was that?" Ink asks.
"What? It was just an act. I wasn't actually going to hurt her."
"IT WAS DANGEROUS THOUGH."
"Blue, it was completely controlled. Nightmare adores her, he wouldn't let anything happen to her, parasite controlled or not."
"Well I could tell that he was fighting with that thing inside him."
"He so wanted to kill me." She says with an eye roll.
"He did. But he wouldn't risk me." You say