After raising the moon, Luna took a few moments to look out over the kingdom as the citizens began turning off the lights to head to sleep. She spotted a few small fillies and colts still running around outside, trying to avoid their bedtime, and a group of four teens heading out on what seemed like it could be a "ponies' night out".
Luna watched them almost enviously. "I hope Celestia and I can make this work," she said out loud, not caring she was talking to herself since it was habit for her by now while on the job. She closed her eyes and transported herself to the dream realm. The first batch of several dreams that passed her were sweet ones, which made her smile as she admired them. One in particular that caught her eye was of Twilight dressed up similarly to Celestia as she attended to Celestia's daily tasks.
"Oh, Twilight Sparkle," Luna laughed. Luna glided through the realm, eying everypony's dreams to ensure they were enjoying their slumber. Eventually, she happened upon a few nightmares, some major and some not, but none anything she couldn't deal with. However, one particular nightmare really caught her interest. It seemed to be of a lone filly, though not one Luna personally knew. She seemed unhappy, so Luna entered the dream to see if she could help.
"Excuse me," Luna said politely as she approached the filly. The filly looked up at her with the saddest eyes she'd ever seen. "Do you need help?"
"Can you bring back my sister?" the filly asked tearfully.
"Where did she go? Was she captured? Taken off?"
The filly shook her head. "She went away because... we don't love each other anymore!"
"That can't be true," Luna insisted. "Did you fight?"
"We sure did," answered a voice from behind. Luna turned around to see a bigger pony, though still half Luna's own height, standing a few feet behind her. "Because Strawberry here thinks she should take everyone's time!"
"You never even look at me unless you're yelling at me!" Strawberry argued, still in tears.
"Stop! Tell me exactly what's going on," Luna told both ponies.
Strawberry spoke first. "Dandelion and I used to play together all the time." The dream began to shift through memories as Strawberry spoke. "Endless days at the playground, games at night, trying to stay up past our bedtimes. We always had fun together. Right, Dandelion?"
Dandelion scoffed. "Yeah, but that's kid stuff. It's embarrassing now. I'm too old for that now."
"That's preposterous!" Luna told Dandelion. "You can never be too old to have fun with your sister."
"We don't like the same things anymore," Dandelion explained. "I have real things to do now. Real grown-up things."
Luna's sarcastic expression could've peeled paint. Just then, the dream changed into a loud club scene, much to Strawberry's fear, and the filly watched as Dandelion walked away into it, sporting an angry glare back at her. She tried to run after her, but her legs were frozen.
"Sissy, please don't leave! Don't leave me alone!" Strawberry begged.
"She won't," Luna said sternly. "This sisterly nightmare is over." Luna lit up her horn and pulled Dandelion out of that loud crowd and over to her little sister. She plopped her down right next to Strawberry, and kept her magic going to ensure she stayed there.
"How dare you disrespect your sister!" she scolded Dandelion, raising her voice, but not using her royal Canterlot one. "Everypony grows up and changes, but you don't ever leave behind your sister."
"But, she-"
A stomp of her hoof made Dandelion think better of arguing. Luna smiled warmly at Strawberry. "Now, let's try to meet in the middle. Name something you and Dandelion can do for big ponies and little ponies."
Strawberry thought for a few moments. "Swimming!"
Luna changed the dream's scene to that of a swimming pool. Delighted, Strawberry hurriedly jumped into the water and called for her sister to join in.
"Well?" Luna asked Dandelion with a smirk, seeing Dandelion was indeed tempted.
"I guess I can join for a little while," she finally said sheepishly. Dandelion jumped into the pool, making a huge splash and amusing her sister. It only took seconds for the two of them to begin playing around with each other. Splashing, dunking each other, and holding their breaths beneath the water. Luna's smirk became a genuine smile as she watched them, and she began thinking of when she and Celestia played together the same way when they were fillies.
"Are you okay?" Luna heard Strawberry ask. Luna looked down to see Strawberry was speaking to her. "Why are you crying?"
"I'm alright," Luna quickly answered, wiping away the few tears she didn't know had appeared. "Have fun. And always make time for your sister."
Dandelion looked fondly at Strawberry. "I promise."
With that, Luna exited Strawberry's dream. She felt proud she helped with Strawberry's sister, but what about hers? Somehow, it only made Luna realize that much more she and Celestia needed that day to themselves. Otherwise, they'd be heading in a similar direction... again.
There was something they still enjoyed together that wasn't about the palace or their royal duties. Something. They just had to find it. Luna would try everything if she had to.
"After all, she's my sister."