"Leave." A small voice, female, and spoken with the firmness of steel. Morning Dew stepped in the same door that Umbra had, moving as if she owned the space.
Luna hiked a brow at the small filly of curious appearance. "Who are you?"
Umbra's horn glowed as she plucked up her foal and drew them right to her lap for proper hugs from behind. "This is Morning Dew, my child. Who... I left back in the Crystal Empire." The logical inconsistency put a crack right through everything. There was no tearing sound, just a sudden silent crack through reality that she didn't seem to notice right away. "What are you doing here?"
"You are having a nightmare." Morning smiled faintly. "And it isn't one I gave you." A clear crime, that. "She did it." Morning met Luna's eyes with no fear. "Release her and leave and we may show mercy."
Luna crossed her arms with a scowl. "You aren't even a unicorn. How are you here?"
"I am the stuff of nightmares," she stated calmly. "And she is mine." She leaned back against Umbra. "As if I wouldn't notice a new nightmare visiting her."
Luna squinted at the little filly. "Is visiting the dreams of others a trick all... All umbrum have then?"
"Only special ones." Morning brought her hooves together. "Like my mother. Now that you understand the situation, will you withdraw, or do we need to fight?"
"Morning, this is Luna." Umbra waved a wing at the spiderweb-fractured vision of Luna, the dream collapsing around her. "She isn't an enemy. Don't be mad at her, she's protective." Umbra squeezed her beloved nightmare filly gently.
Luna suddenly clapped. The breaks were gone, but so was the room at Canterlot. She never went to Canterlot. That was a long way away. Why would she just... go there without warning? That's a silly idea! She was resting in her bed. Morning was snuggled up in her arms. She hadn't been there before. When did that little filly sneak in? Was that how she snuck into the dream with Luna?
And Umbra was still asleep. She knew that, which was an odd thing to know. She was not a lucid dreamer. "Luna?"
"I am still here." Luna emerged from a shadowed corner of the night room, with plenty of options there to select from. "But I have ended my own interference, at the request of your foal."
Umbra sat up, holding Morning, who was still watching Luna with an icy intensity. "Can you explain what's actually going on then? I went to sleep, then I visited Canterlot, which doesn't make a lot of sense, looking back on it."
"I imagine not." Luna smiled at the little nightmare filly. "I would not have thought a being of nightmares would stand in the way."
"Her terror is mine to decide," declared Morning with unwavering conviction. "Why are you bothering her?"
Umbra squeezed Morning from behind. "No need to get hostile with Luna. She's a princess, like me. We're on the same team, even if I'm wondering why I'm dreaming about the two of you." She pointed at Luna. "You have dream magic, so assuming you did that." She nuzzled the top of Morning's wafting mane. "That doesn't explain you."
"Mother, I just said that." Morning did not turn away from Luna, who was being stared at. "Your dreams were being interfered with, and--"
"--And you only knew that because you snuck in." Umbra poked Morning gently. "And you were sleeping right next to me, naughty filly."
Morning colored faintly. "I was standing guard over you."
"With your eyes closed." Umbra was smiling though, not at all upset at the idea of her daughter sneaking in. "Adorable."
"Fearsome," contended Morning, still not facing her. She had a Luna to glare at. "Stalwart."
"Those too." Umbra sat up tall. "Alright, I think I understand now."
"As do I." Luna inclined her head. "I couldn't see who you were sleeping with, nor knew of her talents. I wanted to speak to you alone, Umbra."
Umbra gently pet over the top of her child. "Well, here we are. If you wanted to talk, why not just make me dream I was in front of you to start with?"
"It was... a test. How you traveled. How you reacted to the guards with their suspicions. How you reacted to the food and seeing me in a place of my power. It was all a part of taking proper measure of you." She smiled down at the brave defender. "Until a little somepony interfered."
"I am not sorry." A simple statement of fact and nothing else, Morning sat upright and ready to defend her mother if need be.
"Ah... Well, that's messed up. Did you get what you wanted to learn out of it?" Umbra shrugged softly. "Are we swapping spells or not? I don't know if dream books work properly for that."
"They do not." Luna perked an ear. "Unless you were already in the habit of perfectly recalling spells in your sleep. All I could see were remembered fragments and glimpses. Tantalizing, but not helpful. Neigh, we will have to meet in person to properly exchange spells."
Umbra sat up with a smile. "That means you want to swap spells?"
"I do... You have learned a few I would gladly add to my collection, and I have a few you would care for. It is in the interest of our ponies that we do this. When next can you make time to visit... for real?" Luna had her eyes on Umbra, ignoring Morning, or at least not meeting her eyes. "I will not trouble your dreams again. You clearly have capable guardians of your own."
Umbra began to clap with undisguised joy. "I'll have to get someone to watch over Morning."
"Why?" Morning finally looked away from Luna. "I can accompany you, mother. Besides, I wish to meet this other nightmare bringer. She isn't one of us..."
"No... She is a pony, but a nice pony." Umbra touched her nose to Morning's. "And that wasn't a nightmare, even if she was messing with my dreams a little. She's an anti-nightmare, as a rule."
"I am a mare of the night, if that helps." Luna looked more amused than much else. "If you want a daymare, you will have to seek mine sister."
Morning twisted back to give Luna the glare she clearly deserved. "You will not bother her dreams again." That Luna did not seem properly scared didn't change her convictions.
Umbra stood up over her daughter. "Alright then. I'll make arrangements, and you can consider yourself warned. I may come with Morning Dew, or not, still undecided on that."
Luna dipped her head. "Then I will leave you to rest." She lifted on her large wings and vanished out the window that hadn't been open a moment before. "Sleep well." And she was gone, back to the realm of dreams to visit other dreams, one imagined.
"Now you." Umbra poked her brave defender of a daughter. "Thank you for being ready to protect me, but is this even the first time you snuck in?"
Morning flipped her ears back, shrinking from Umbra's accusation. "Well..."
Answer enough. Umbra poked Morning anew. "Stop that! If you want to sleep with me, ask. I'll say yes or no, but no sneaking in. The only exception is if you have a bad nightmare, but I doubt you'd ever have one of those. As if anything could out nightmare you."
Morning flashed a predatory smile at that. "As if." She rubbed behind her head. "My apologies, mother... Once we were asleep, I could feel Luna's presence. I became worried for you, and began... I snuck in again, this time to your dreams."
"I didn't even know you could do that." Umbra leaned in, almost touching noses with her child. "What a talented filly you are. Can all umbrum do that? Wait." She skewed an ear off. "Can I do that?!"
Morning turned her ears away. "I could try to show you, mother. When we're awake. The nightmare is past. I should let you sleep."
"You just want to get away." But Umbra let Morning escape from her grip. "See you in the morning."
"Sleep well, mother." Morning bowed low and vanished like someone made an editing error in the universe, just gone in one moment where she was the moment before.
"That was creepy." But Umbra knew that would only please Morning to know. "I have such a talented child." She threw herself back onto her bed and snuggled in. "Now... to go to sleep, in sleep..." How did that work?! Fortunately, with no other presences and just relaxing, her natural dream cycles returned on their own, and she casually slipped into the next dream without even noticing.
Shifting mussed the head of their child. "I can keep an eye on her."
"I wish to accompany you." Morning had not changed that desire, not one bit. "I can protect you, and it will be 'educational'. Do you not want that?"
Umbra chuckled softly, looking between her two beloved. "I'd rather take you both along..."
Shifting perked her ears. "So why not that? I don't have a day job that'll miss me."
Morning nodded. "And she can assist with foal watching." Not that she appeared to think she needed much watching. "And we can both help you, mother."
Umbra clopped a hoof to her face. Betrayed! "You two! I swear. It's a good thing I'm stupidly in love or this would annoy me." She delivered a kiss to either of their noses. "You two really want to come with me so bad?"
Shifting flapped her leathery wings. "Yes! Besides, you'll need somepony to test your new magic on." She patted herself on the chest. "And who else would that be?"
Morning rubbed her hooves with a slightly worrying smile. "I would like to see that. Besides, I hear Canterlot is very different from the Crystal Empire. I would like to see it as well. Besides even that, I also want to meet this 'Luna' face to face."
Umbra frowned at her daughter. "You will not start a fight with her! She's coruler of the lands, and a nice pony so far I can tell. Be nice."
"Only after she apologizes." Morning crossed her arms. "Entering my mother's dreams is very rude, especially on an information gathering mission."
Shifting looked between the two. "Did I miss something?"
"Ugh!" Umbra threw her hooves wide. "She came to visit me one night. Nothing bad happened. In fact, it's because of that that we have an immediate invitation to go swap spells. I want to meet her."
Morning's guarded expression lifted into a clever smile. "Oh. You wish to exploit her. Mother, I misunderstood. I will not interfere with your espionage."
That wasn't exactly what Umbra had in mind, but... "Alright. Good. We have an understanding."
Shifting pranced away with a merry whistle. "I'll pack! When do we go?"
Umbra realized she had been trapped in the flow of things. "Let me talk to the royal couple so they know what I'm doing. Won't do to have their shadow guardian vanishing on them." She started for the door and rapid clip-clops told her there was a Morning right after her. "Oh, right."
"Yes, mother?"
"I will get your schoolwork." Umbra peeked to the side at Morning. "We can't have you falling behind, even if it's an educational trip."
Morning wrinkled her nose. "Yes, mother." She assented even if she looked a bit put out by the news. "I will defeat the home schooling thoroughly if it thinks it can stop me from reaching my goals."
Umbra ruffled the top of Morning's head. "That's the spirit. I knew I could count on you to win this battle."
"Are there any umbrum in Canterlot?"
Umbra came to a halt with a frown. "Not that I know... of? You're probably better at spotting them than I would be."
"With pleasure, mother." Morning dipped her head, a little smile on her face.