Everyone wanted “Dove looses her sh*t” on my poll so here you go~ This is where Nightmare kicks in
 

 
Dove: No…. n-no….
 
Nightmare: Hello, Dove. Nice to see you again.
 
Dove: Fichez-moi la paix! (Leave me alone) I just want to sleep.
 
Nightmare: These nightmares wouldn’t be a problem if you just took me up on my offer.
 
Dove: How could I do something so awful? Va t’en! (Go away!)
 
Nightmare: Oh my sweet Dove, you’re not understanding that this is for the best.
 
Dove: The best? H-how?
 
Nightmare: Can’t you see? Everypony around you is afraid of you.
 
Dove: Yes… I know. But how would allowing you to take over make them any less scared of me?
 
Nightmare: You’re failing to see the issue, Dove. They will always be afraid of you so long as you’re so powerful and out of control.
 
Dove: Th-they’re going to figure out how to help me. Starburst says everything’s going to be okay.
 
Nightmare: What if they don’t figure out how to help you? You will only get more and more out of control and your outbursts will become more frequent.
 
Dove: But they–
 
Nightmare: You’re their friend. They’ll keep trying to help you until the very end. And if they can’t help you, you’ll be too far gone for them to stop you. You’ll destroy Equestria.
 
Dove: It’s not true. I’m not that powerful. There’s no way…
 
Nightmare: Stop trying to deny it, Dove. You’re underestimating yourself. You have the strength of an alicorn thanks to that Alicorn Amulet your mother, Trixie abused in the past. On top of that, you have the strength of your other mother, Starlight, a very formidable unicorn. And without control, when released, your magic is pure, unfiltered power that can only bring destruction.
 
Dove: …………. If you become a part of me, what are you going to do? I haven’t heard good things about you.
 
Nightmare: Goodness you’re stubborn. This is a bargain, Dove. It’s clear that I want full control of Equestria–
 
Dove: And why would I let you have that?
 
Nightmare: Because an Equestria under my rule is still Equestria. If you continue to lose control, you will go berserk, and destroy it and everypony you love. Your body was not meant to contain so much magic. Together, we will have the capacity to do so.
 
Dove: I… don’t know…..
 
Nightmare: I have been stopped before. If I have control at least your friends and Equestria will have a chance.
 
Dove: …………………….
 
Nightmare: It’s up to you, my dear. Either let your friends keep trying to help you and risk letting your unknown powers get more out of control, leading to the destruction of Equestria. Or, alternatively, let me become a part of you to achieve my goal. If I’m defeated as I have been in the past, my essence will be diminished from you along with the effects you’ve suffered from the Alicorn Amulet.
 
Dove: You… can take the that away?
 
Nightmare: I feed on the magic of my hosts. If I am expelled from you, I take all your magic, and corrupted magic with me.
 
Dove: What if it comes back?
 
Nightmare: It won’t. Only your natural magic shall return. And even if it does, it will give your friends more time to figure out what’s wrong with you.
 
Dove: …………
 
Nightmare: They fear you, Dove. Let me take control. Let them fear me instead. They won’t blame you for what I do.
 
Dove: …………………….
 

 
Nidra: Pretty quiet tonight. Should probably call it a day. Er… night. Whatev– ACK! W-what was that? Feels like… Dove?
 
flies over to Dove’s home
 
Dove: tossing and turning
 
Nidra: Seems like a bad one horn glows and teleports into Dove’s dream
 

 
Nightmare: Are you ready to give in?
 
Dove: I can’t……
 
Nightmare: You truly are selfish.
 
Dove: I…. I’m not evil.
 
Nightmare: Saying you’re not evil will not justify your actions in the future. You mean no harm but you will harm anyways.
 
Dove: starts tearing up and horn glows red Ah, no…
 
Nidra: Why can’t I change this nightmare?
 
Dove: looks over N-Nidra?
 
Nidra: …………. looks around Me? You can see me?
 
Dove: What are you doing here? You need to get out.
 
Nidra: I– Wow. Um…. this is new. I’ve never talked to anypony in their nightmares before. I’m not usually able to interact with them.
 
Dove: This is no ordinary nightmare, Princess Nidra. You need to leave. S’il vous plait. (Please)
 
Nidra: Dove, this is my duty. I’m going to make sure you’re rested. I can figure something out.
 
Dove: Princess Nidra you don’t understand. You’re not safe here.
 
Nidra: It’s just a nightmare, Dove. You’ll be okay. We’re both safe here.
 
Nightmare: Don’t you see, Dove? No matter how much you tell them to leave or how much they’re scared, they won’t give up on you. They’ll stay close to you and you’ll hurt them as a result. Give in.
 
Dove: N-Nidra I’m dangerous. Allez-vous-en! (Go away!)
 
Nidra: I’m not going to leave you here. You’re a dear friend to Starburst and she’d kick my ass if she knew I let you endure this torment.
 
Nightmare: You’re running out of time, Dove. You’re going to lose control again.
 
Dove: Nidra I can sense that you’re afraid of me. I–
 
Nidra: Oh, that’s only because you’re afraid. I feel whatever you’re feeling while in your dreams. I’m learning to control it better. I’m not afraid of you, see? walks closer to Dove
 
Dove: I know you’re afraid of me! I know all of you are afraid of me! Why won’t you stay away?!
 
Nidra: Because we care for you, Dove. reaches to touch Dove’s shoulder Everything will be okay.
 
Dove: Stay. BACK! releases a powerful pulse of magic
 
Nidra: AH!
 
Dove: …………….. n-no.
 
Nidra: tries to stand Ah winces My leg….. ahhh.
 
Nightmare: You’re a monster, Dove! You’ve injured on of Equestria’s royals. Everypony you know will hate you for this. You NEED me! You will do much worse than this if you allow this to keep happening.
 
Dove: ……………… sits down and surrenders Je suis désolé….. I’m sorry, everypony
 
Nightmare: Fool.
 
darkness consumes Dove
 
Nidra: tries to shoot at the dark clouds I’ll get help, Dove. Hang in there. teleports out of the nightmare
 
Dove emerges, taller, with a black coat and longer horn
 
Nightmare Dove: Hmmm…. Even more powerful than I anticipated. Excellent. Time to give Equestria the greatest show it’s ever seen.