Sleep evaded Princess Luna. For what seemed like the past several hours, she had laid awake, staring at the ceiling. When that didn't work, she had rolled over on her belly. And when that failed as well, she carefully rolled to her side. Still nothing.
This is an exercise in futility, Luna mentally huffed. But, I need sleep, to carry out my duties tonight. Argh, this is so FRUSTRATING! Grabbing a pillow, she brought it down over her head. With her head buried, the world was a bit quieter, but sleep still failed to come. But what did reach the Princess was the faint sound of knocking on her chamber door. Her head snapped up from beneath the pillow, and she rounded on the noise. "WHAT?!" she barked at whoever dared disturb her attempt at slumber.
"Princess? Did I wake you up?" the voice of a certain pegasus mare called quietly, and Luna instantly felt bad for snapping at her.
"No, you didn't wake me, Derpy," Luna replied in a calmer tone as Derpy pushed the chamber door open. "I was already awake."
When she had appeared in the doorway, Derpy had a smile on her muzzle and a happy little glint in her eyes. But they both faded and gave way to a look of confusion and concern that Luna was up at this time of day. Trotting to the window, she peeked around the heavy blackout curtain and regarded the Sun's position in the sky for several moments. Replacing the curtain, she started walking toward Luna's bed. " 'Already awake?' At this time of day?"
"I meant still awake, dear," Luna sighed, lowering her head back down to the bed. "Sleep eludes me."
"Oh no!" Derpy gasped, rushing the rest of the way to the bed. "That's awful, you poor thing," she cooed softly over her royal marefriend as she clambered up on to the bed and laid close to Luna. "Are you not feeling well? Maybe get you some soup?"
"I appreciate your offer, but I am in fine health. Just..." Luna sighed, "...tired."
Derpy and Luna laid beside each other, not saying a word for several moments, until the silence was broken when Derpy quietly asked, "What did you do before bed?"
Luna thought for a moment. "Well, after my duties were completed... I stopped in the Dining Room to greet Celestia and fill her in on any news... had a croissant on the walk to my chambers... and I've been attempting to sleep the rest of the time."
"Did you try anything to help you sleep?"
"Yes, I had a glass of warm milk."
"Hmm." Derpy pondered for a bit, while Luna stayed laying down, enjoying the company of her marefriend at her side. Finally, Derpy turned and regarded Luna with a thoughtful gaze, her head tilting slightly to one side. Luna thought she looked adorable, and nearly said so, but Derpy interrupted her train of thought by asking, "Do you always wear your shoes and tiara and...?" Trailing off, she gestured vaguely at Luna's peytral.
"It's called a 'peytral', dearest," Luna supplied, sitting up and giving a Derpy a light peck on the cheek, making the pegasus blush an adorable light pink.
"Your pe-... Pey-... Pie...? Your necklace?" Derpy stuttered and finally decided.
Luna giggled lightly at her marefriend, and nodded, "Yes, it is a habit I've fallen into, going to bed with my regalia on."
A satisfied nod from Derpy was the only reply before she stood and climbed off the bed. "Well, you should take it off, then. That extra weight can't be that comfortable." She turned and sat down, watching Luna, waiting for her to get up. Patting the floor beside her, she smiled. "Come on, let's get you ready for bed properly."
Luna slowly stood and stepped down to the floor. At Derpy's gentle prompting, she removed her ceremonial shoes, placing them in a neat row. Next came the peytral, slid over her head and placed on a mannequin meant for such things. Finally, her tiara was removed and also placed on the mannequin.
Derpy stood with a smile. "There. Doesn't that feel better? Lighter?" She took in a deep breath and slowly let it out. "More relaxed?"
Luna breathed deeply, and found that she did actually feel lighter. She fluttered her wings a bit and smiled. "Yes, dear, it does feel nice."
A beaming smile crossed Derpy's face, and she pointed a hoof at the bed. "That's good. Now, into bed," she cooed, helping her royal marefriend get settled. A pillow fluff here, a blanket adjust there, and Luna was as comfortable as could be. Derpy stepped back to admire her work, before turning to scrounge around the nightstand. "Do you have a brush?" she asked.
Luna's magic pulled the drawer of the nightstand open, revealing the brush. "Will this do?" she giggled.
"Only perfectly," Derpy smiled, grabbing the brush and making her way back to the bed. She climbed up and settled close to Luna's side. But, she didn't begin brushing.
Finally, Luna's curiosity got the better of her, and she turned to look at her marefriend. What she saw made her giggle quietly. Derpy had the brush in her raised hoof, ready to work, but she wore a confused expression on her face as she contemplated how exactly to carry out her task. Luna's mane was not like any normal hair she'd ever brushed. It seemed more like water, or smoke. Eventually, Derpy looked up and met her royal marefriend's eyes, wordlessly asking for guidance with an embarrassed grin.
Luna giggled again, and said "You're so cute when you're confused, hon." She reached up and gently booped Derpy's nose, which made her chuckle. Laying her head back down, Luna assisted Derpy with, "It appears more intimidating than it actually is. It actually behaves more like real hair, despite its appearance."
With that helpful tidbit of information, Derpy smiled and gave a nod. She gently placed the brush on a spot near the base of Luna's mane (she hoped) and slowly pulled the brush through the astral void, going with the grain (again, she hoped.) If the content sigh from Luna was anything to go by, her hopes were paying off.
After nearly three minutes of steady, gentle brushing, Derpy felt Luna relaxing more and more. Quietly, she began to sing to her marefriend-
Stars and moons and air balloons
Fluffy clouds to the horizon
I'll wrap you in rainbows
And rock you to sleep again
Luna, teetering on the edge of consciousness, vaguely considered the lullaby. It seemed familiar, perhaps from a foal's dream? It was not important right now, though. She could figure it... out... later... Zzzz
Derpy continued humming her lullaby and gently brushing Luna's mane, until the hypnotic combination tugged her to the realm of sleep. She stayed just awake enough to put the brush on the nightstand, and drape a wing over her marefriend's back, before falling into a peaceful slumber.
As they both dreamed, the two ponies smiled and nestled closer to each other, enjoying the most wonderful sleep either of them ever had.