"... Lieutenant Captain, you seem depressed tonight. Pray tell what is wrong?"
"My conversation with Moon Dancer didn't work. I was afraid it wouldn't work, Your Majesty."
"In the days before our exile, we would travel in the dreams of young ponies to help them in facing problems they may have. We do not currently know if we have regained this power yet, but perhaps Moon Dancer could make a good trial subject?"
"Your Majesty, even if you could, I don't think it would help in this case."
"Oh? And pray tell why not?"
"Well, I think it's best to start from the beginning..."
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EARLIER THAT EVENING...
It was now hallowed ground. There was no official proclamation of Celestia, but it seemed to have been mutually agreed upon that the library where Twilight Sparkle resided while training under Celestia was to be kept in a pristine condition as an honor to the filly that had saved Equestria from calamity. It was deemed a proper show of respect that she would have a place to return to should Celestia allow it.
Even though Shining Armor was Twilight's big brother, he still felt he needed to lead by example in keeping his distance, only approaching with slow step. There was no formal guard posting, as the information in the library's books was too important to completely seal off, but instead a simple sign telling anypony that went by the identity and heroism of its former occupant as well as plea for treating the space with respect. The door was left open, though, and Shining stopped just outside the doorway to see if the pony he thought was in there was indeed in there.
Looking at Moon Dancer studying a book in the library was for Shining Armor like looking at a strange alternate universe version of his sister, sending a chill down his spine. After joining Celestia's School for Gifted Unicorns, Moon Dancer started wearing her mane and tail in a style resembling Twilight Sparkle's, as well as getting a pair of "reading glasses", and the resemblance only started growing over time. Now looking at her, Shining Armor was alarmed to see the same behavior patterns Twilight had setting in. He was glad he had not come wearing any armor, but wished he had somehow found a way to get the present Spike was going to give her.
As Shining stands just outside the doorway, the glasses and sweater-wearing Moon Dancer looks up from her book in Shining's direction. Her expression gives Shining a distinct impression of unwelcome hostility, first by her eyes moving in a scanning manner and then an angry glare as her glasses are levitated off her face to be set aside nearby.
"I know who you are. Go away." Moon Dancer finally speaks, her voice with growly undertones of hostility.
"Look, I know what you're thinking Moon Dancer, and I'm not here to apologize for my sister." Shining replies, moving just inside the doorway of the library.
"I know what she did is wrong, and it hurts me she wasn't interested in parties or hanging out in general with other fillies her age. I'm hoping she understands now, even though there's no way to turn back the clock."
"You can say whatever you want, I'm not going to believe you. Not after I went through all the trouble to throw a party and she never showed up! And then her leaving on some mission sent by Princess Celestia without so much as a goodbye!" Moon Dancer replies acidly.
"Moon Dancer, I know you're upset, I would be too, but I'm here because your mom is worried about you! She wants you to at least talk to her about it!" Shining almost pleads in response.
"Hah, that's rich. After learning about my sister, I don't ever want to talk to her again!" Moon Dancer says to blow him off.
"Sister? What are you talking about?" Shining asks as his expression suddenly changes to worried puzzlement.
"Oh, you've probably met her before - the 'special friend' or 'special playmate' my mom sometimes referred to. She never told me she was my sister though."
"Then how did you learn about it?"
"Zodiac showed me evidence the 'special friend' was my sister. We have the same mother but different fathers, according to him. My mother wanted to keep it covered up because she wasn't sure who the real father was. She's been lying to me my whole life about her, so why should I trust her now? She's hurt me, just like your sister hurt me!"
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Shining's concern had now changed to alarm. He had trouble believing that Star Dancer had been covering up such a situation from everypony else for so long, and there was a very good possibility Zodiac was trying to drive Moon Dancer toward him and away from other, more positive influences. What's worse, he had no way to counter the argument she was making.
"Moon Dancer, I... I'm not sure what to say about that..." he finally tries.
"There's no more point in continuing this conversation." Moon Dancer abruptly states as she rapidly gets onto four hooves, her eyes angry embers of emotion. "If you wanna help, bring your sister here and have her apologize to me!"
"Now you know I can't do that because of Princess Celestia..." Shining tries to explain, only to get cut off again.
"Buck Celestia! I've already decided to drop out of the school! I don't need anything but my books and a private place to read them in!"
"Moon Dancer, please..."
"I've had enough talk! If you can't bring your sister here, get out!"
"...What?"
"You heard me right, turn right around and get out right this instant!"
"Moon Dancer, you can't...!"
"GET OUT! GET OUT RIGHT NOW!" Moon Dancer shouts at the top of her lungs, accompanied by the magic tossing of several books at the same time in Shining's general direction.
None of the books hit their mark, but it's enough to convince Shining the cause is lost. He looks back and forth from the tossed books to Moon Dancer's fuming anger, taking a few breaths to keep his emotion in check. Finally, he manages to lock Moon Dancer straight in the eye.
"Alright, alright Moon Dancer. I'll get out and leave you alone." he speaks softly, utilizing a calming tone that was previously sometimes used to soothe a frustrated or irritated Twilight. "But please, at least talk to your mother. Don't make her a casualty of my sister's mistakes."
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BACK IN THE PRESENT...
"How terrible! Do you really believe that she intends to isolate herself from all others?" Princess Luna asks Shining Armor.
"Yes, Your Majesty, I do." Shining sadly replies.
"And the claimed affair that produced a half-sister?"
"I... don't know. I'd have to look into the records."
"And what are you going to do now?"
"The only thing I can do: write my sister a letter." Shining replies with a determined look on his face. "Maybe she'll be shocked into sending Moon Dancer a written apology. It may not work, but it's better than doing nothing."
"I agree. Anything is better than nothing when past sins need to be rectified. I hope one day to do this for the general populace of Equestria as well, not just here in Canterlot." Luna says with a smile.
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MEANWHILE...
Moon Dancer, still in the Canterlot library reading books, looks up upon hearing a knocking noise. She sees an inky blue pegasus stallion about her age is making the noise by knocking one of his forehooves on the opened door.
"Oh, at least you gave the courtesy of knocking Zodiac. Come in." Moon Dancer says in the stallion's direction.
"What's the matter? What happened?" Zodiac asks as he steps over beside Moon Dancer.
"Twilight's big brother had the nerve to visit me here earlier! He left after I gave him a piece of my mind!" the unicorn mare replies, a glare under her reading glasses as she looks at Zodiac.
"Oh, him?" Zodiac asks, chuckling a bit. "I don't know what everypony sees in him. He's like Charlie Browncoat - all wishy-washy. I wouldn't worry about him, there's nothing he can do here."
"Well, you don't need to tell me that. What are you doing here anyway?" Moon Dancer asks in a casual tone as she flips over a page in the book in front of her and continues on reading.
"Your mom gave me a day off tomorrow, so... I was wondering if you wanted to hang out at Pony Joe's with me?" Zodiac asks awkwardly, looking away and rubbing one of his forelegs on the back of the other foreleg.
"Really?" Moon Dancer asks hopefully, perking up her mood for the first time that day.
"Sure, why not! Besides, when was the last time somepony, particularly somepony like Twilight Sparkle, invited you out?" Zodiac asks with a grin.
"Well, nopony really has... Twilight never did, I can't remember any others besides my mom..."
"Exactly! I'm not going to be a jerk like they were! I promise, I'll always come to whatever party you want to throw."
"Thank you, Zodiac. I really appreciate that." Moon Dancer says, a rare smile crossing her face.
"Tomorrow afternoon, then? Oh, and don't tell your mom about this conversation."
"Don't worry, I wasn't intending to anyway."
"Good! See you at Pony Joe's tomorrow evening!" Zodiac states as he turns to leave the library.
As Zodiac exits, he looks back at Moon Dancer returning to her reading, albeit in a much better mood than before. He keeps his excited look on his face until he is out of Moon Dancer's sight, then the expression changes to a "got her where I want her" expression. The trap would soon be set for both mother and filly to fall into...