Luna just looked on in shock with her head yelling, 'Nononononononon' as her alter ego is given new form. 'By the heavens Darkmoon why have you done this?'

Meanwhile the former Darkmoon reveled in her new power. 'Yes, with this power I shall protect my children. Then we shall take our rightful place. Before that could get further one of the lookouts reported in. “We have a very large force heading for us.”
“Well they will learn that the Children's mother has returned. Everyone to you defense stations!” With that Nightmare moon rose to the sky and flew towards the approaching force. A dark cyan beam emerged from the black alicorn's horn cutting a huge swath in the enemy force followed with a whirling and several lighting bolts. The Children looked on in awe and Luna a serious expression as the fight was out of their range. Luna looked around her at the ponies looking at the battle. She then looked at Nightmare moon and frowned. She was making great progress flying through the dwindling ranks of the enemy. Even a being such as Nightmare Moon couldn't do it alone and as much as Luna hates what she represents she was defending the Children and she just might get to Darkmoon and get her back. She took off to assist her alter ego.

A creature swipes at Nightmare Moon's head then jerks her head back and impales her horn in the head of the creature killing it instantly. She saw another coming when a blast destroyed it. Looking back She saw Luna closing in. Nightmare moon smiled at the sight of her child coming in to help but the sight of her cutie mark caused her unease. She felt like she should despise it but couldn't remember why. Well that could wait and together they decimated that enemy force. Finally what was left of the enemy force were retreating but that was not enough for nightmare Moon. With her ethereal mane she caught one of the creatures and brought it close. “Now listen carefully creature. Tell me where you base from and you won't suffer.”
“I will tell you nothing ACK!” Nightmare Moon tighten her grip on it's throat. “Dear Luna I wonder how long till it's head pops off?” The black creature struggled a bit more but giving in.
“Alright, ALIRIGHT! We are staging in the Kepuor mountains on the right now please stop.” Nightmare moon smiled.
“Thank you for your help.” With a quick twist she snapped it's neck and allowed the body to fall. She then looked at Luna. “I promised it wouldn't suffer not it wouldn't due. Now come on time to nip this threat in the butt.” The two flew to the northern mountains. They arrived in an hour and Nightmare Moon told Luna. “Keep them off me while a charge an attack. The smaller alicorn nodded and intercepted a defending force. Nightmare Moon then began charging. Her eyes glowed white and a white field appeared beneath her hooves. A dark cyan glow surrounded her horn and that was all she knew till she felt it was ready. “LUNA! MOVE!” She felt the alicorn zip out of the way and she pointed her horn at the base and unleashed a blast of magic energy. It was twice as big as herself and contained the bulk of her energy. The resulting explosion was the biggest anyone has ever witnessed. With nothing but a smoking crater Nightmare Moon nodded and began the trek home with Luna by her side. “Thank you for your support Luna.”
“I did for the Children.” Luna said coldly.
“Why are you so cold to your mother?”
“Because you are not my mother.” Luna sighed. “Look Nightmare Moon, We have severely helped the Children and they deserve a night of celebration. My issues with you can wait.” Nightmare moon nodded and the two head for the compound.

When they returned there was great cheer among the Children. Luna quickly walked away from the crowd heading for the forest area again. “Luna, you okay?” The princess looked over to see Nightshadow looking concern.
“I am not my friend. Please give your fillies a kiss for me. I will not be joining you tonight. Darkmoon has chosen a path that I would not wish on any pony and I need to be as ready as I can be for her.”
“Why? She has become the Princess of the Night, what could be bad about that?”
“She has become the dark side of the Princess of the Night and that is not good. But there is hope. Goodnight my friend.” Luna flew away before Nightshadow could ask any more. She found the clearing again and with more desperation then ever to reconnect to the moon.

Meanwhile Nightmare moon entered Darkmoon's chambers. They will serve for the time being as hers. Besides it felt familiar, She maybe Nightmare moon but a part of her will always be that brave pony who has given her body for her Princess. She took off her armor and had to do some rearranging to make a bed big enough for her form and she laid down and grabbed a book to read to tired herself out. A knock on the door interrupted her. “Come in.” The door opened and an Earth pony mare came in.
“Pardon me Princess Moon but I thought you would like a bite to eat after your efforts tonight.” That caused Nightmare moon to smile.
“That's not a bad idea, thank you.” The Earth pony, Night Hammer she recalls from Darkmoon place the tray down and nightmare moon started eating. In minutes she noticed a concern from the Earth pony. With a sigh she stated.
“You have a question night Hammer. Please ask it.”
“I'm sorry your highness but I wonder if Darkmoon was in there with you?”
“I'm afraid not. I have her memories added to my own but I am not her I am Nightmare Moon but that doesn't mean I don't consider you a friend. Honor her sacrifice, I do and any friends of her our friends of mine.”
“Thank you for your honestly your highness.”
“You are quite welcome my child. Tonight's the start of a new era for my children and Darkmoon made it possible.” Night Hammer left after that and with a yawn Nightmare moon laid down to sleep dreaming of the coming days.

The next evening Nightmare moon called everyone together for a meeting. Luna herself went to bed when day came and sadly still in her unbound form. She gathered with Nightshadow and Twilight Moon and Eclipse. She feared what this Nightmare Moon will say, she had to protect her children. With everyone gathered Nightmare moon began. “My Children tonight truly starts the beginning of a new era. We will rest and rebuild ourselves then we will go to Equestria and take it over from the sun loving faces of those ponies and bring about Night Eternal!”
“YOU WILL NOT NIGHTMARE MOON!” Many gasped and moved away as Luna approached the black Alicorn.
“Luna why? After last night I thought you be among my greatest supporters.”
“Last night you were defending the Children of the Night which I could support but this I can not. Look around you, the Children have fought long and hard against those creatures and are depleted and you want to go against Equestria? Not only will you have to face the princess of the Sun, MY SISTER Celestia but the Princess of Friendship Twilight Sparkle and the Royal Guard. I plead to you Darkmoon to not go down this path. I did, I WAS Nightmare Moon the first Nightmare Moon and that is a path of jealousy, hatred, and is ultimately self hurting. Darkmoon do not got down this path, you have power but don't use it this way.”
“I will not have you deny us our right and I AM Nightmare Moon the Princess of the NIGHT!” Luna closed her eyes and sighed.
“Then you leave me no choice, goodbye Darkmoon.” She took to the air. “I Luna, the true Princess of the Night and co-ruler of Equestria I will do all in my power to stop you.” With that she charged and attack and fired on Nightmare Moon. Nightmare moon raised a shield and the attack hit harmlessly.
“YOU FOAL!” Nightmare Responded and fired her own beam and Luna raised her own shield that held. But Nightmare wasn't done and poured more magic into her attack. Luna's shield began to crack so he put more magic into it and it was repaired and with more magic glowing from her horn Luna teleported and appeared behind Nightmare and blasted her in the back before flying away. “AAAARRRRGGGGHHHH!” Nightmare screamed in pain then her eyes went white and did a quickly blast that hit Luna dead center. Luna lost her shield when she teleported and thought she could dodge any attack quickly. The attack blasted her out of view. Nightmare Moon then looked at her Children. “Let that be a lesson my children. Do not oppose me but with me by your side we can do much now get ready.” The crowd dispersed and Nightshadow ran in the direction Luna flew.

Nightshadow raced through the woods trying to find Luna, Twilight Moon and Eclipse huddled on her back. A bright light of dark cyan appeared ahead of her and she raced in that direction hoping that Luna was okay it took her a half an hour to finally get to a small clearing and spotted a bluish form on the ground. She raced over with her kids hoping off her back. “By the moon Luna, please be alive.” She activated her horn and her healing spells and got started on the alicorn trying to heal her wounds. She was in bad shape with scorched marks all over but she was alive. She can survive this she HAD to. She survived worse. “Please Luna don't leave. I rather serve you than Nightmare Moon. You have always shown care and compassion for us. You've always been in the thick of it defending us and even this last fight was you trying to protect us. Nightmare Moon seems to be more interested in power and revenge and I fear she will destroy us with that thirst. She may be the Princess of the Night but you deserve it more. Besides you have your nieces to help me take care of and......and I need you.” Nightshadow began crying and her tears dropped onto Luna's body. Even Twilight moon and Eclipse cried with their adoptive mother. Unbeknownst to them something was happening to the moon. It was in crescent form this night it now has gone to Full moon and suddenly a narrow beam of white light shot from it and onto Luna. Nightshadow and the fillies backed off and Nightshadow looked at the moon. “By the night!” The White beam pulsed where Luna laid and Nightshadow felt a massive increase of magic. She couldn't even see Luna in there just a beam of white. After a few minutes though a figure stood in the beam. Taller then the average pony the being had a pony form and the beam ceased and Nightshadow looked on in shock and manage to say. “It was true, it was all true.”

Author's Notes:

I little short I know but i had to end this chapter there