After several more hours of far more pleasant conversation, Luna departed Twilight’s pleasant company. However, Luna did not teleport back to her wing of Canterlot Castle.

Sometimes, troubles could not be solved through a simple conversation. They required further thought. And with the poignant reminders of her past cropping up in her reviews of Equestria’s recent troubles, an idea had begun to form. An idea that required her to step into her own past.

More specifically, to step into the Castle of the Two Sisters.

The relic of bygone ages remained as it always had since that fateful night: weathered, worn, crumbling, yet still standing after a thousand years. Celestia had once opined that the Tree of Harmony was responsible for its longevity. After all, the Everfree should have reclaimed the castle fully long ago.

Luna had wondered if there had been reasons.

She walked through the dusty corridors, wondering what would become of this place with the Tree’s fall. It’s ‘sapling’—for lack of a better term—had grown in its place through the aid of Twilight’s students, yet she suspected the ruins would not remain as they had been.

It was a somewhat melancholy thought, but as she wandered deeper into what once had been her home, most of her thoughts were in that vein.

An idle wind fluttered tapestries and swirled leaves in a section where the roof had collapsed. She paused there, her eyes having no trouble seeing in the gloom. It took her a moment, but she spied the worn sigil of the moon above the leftmost passage.

A few minutes later, she brushed a specific piece of wall with a wingtip. To her surprise, the hidden door still functioned as it rumbled aside, revealing a dark corridor.

It was the one that would lead her to the place where she had changed the world—and not for the better. She sent a small moon of light floating down the pitch-dark corridor into the earth, then followed it, her shoes clacking against the stone.

“How long it has been…” Luna whispered to herself as the door closed behind her. “I wonder if the Tree undid the magic I wrought here…”

Idle speculation, but important nonetheless. Twilight’s latest experiment—specifically the one demonstrated this very evening—had used the very foundations of reality as foci, powering a runic circle that could glimpse into the home of distant allies in an attempt to copy the fallen Storm King’s long-distance message spell. It had been a success, though a short-lived one. Further fine-tuning would be required as the ash-covered Twilight could testify after speaking briefly with Queen Novo.

Thoughts of that circle had summoned far more memories than a simple newspaper could. Memories of another time, but of this place.

Her moon swept out of the corridor and into the great chamber. Luna had believed herself ready for the sight of it, but she as she laid eyes upon the birthplace of Nightmare Moon, she found herself sorely mistaken.

Set directly beneath the castle’s throne room, the vast chamber had once been used for little more than storage. That had changed the day the Crystal Empire had vanished and the dark King Sombra’s words had unlocked something within her. Ancient thoughts of rage, jealousy and hate echoed through her as she beheld the crystal-lined ceiling. Even after all these years, the crystals still shone with a dim blue light. Between them and her little moon, the rest of the chamber was revealed, including the crystalline veins in the rock that led to an immense circle upon the floor.

Runes in a language even Starswirl himself had all but forgotten lined the vast magic circle in the center of the cavern. Though it held no power, Luna could still see it glowing with a blue-black light in her mind’s eye. She remembered the test, the one that assured her that she should have won that fight so long ago. The shadows had made promises, shadows from the depths of the earth and the depths between the stars.

They had lied.

Luna stepped forward and asked her tiny bright moon to flare, bringing brilliant white-blue light to the chamber. There was little else beyond the circle, save for a few tables, a handful of ancient books and some leftover reagents of her spellcraft. All exactly as she remembered.

Swallowing hard, Luna knelt and touched the circle. “I fed you darkness, from myself and beyond, and I reaped nothing but sorrow for so many.”

She thought of Twilight and of her kind words in defeating her own demon borne out of the need to cause herself pain for her transgressions. She had grown since that day.

Luna looked up at her miniature moon and smiled.

“I will not fail again.”

This had been in the back of her mind for months now, long before Sombra’s attack on Canterlot. A question. Perhaps it was fate that Twilight had provided the last piece of the puzzle this very night. The savior of Equestria a dozen times over had given Luna the key to saving it forever.

She hesitated only a moment. Once, the power in this circle had crept up into the ceiling, filling her with dark power as she faced down her beloved sister in an insane coup.

Now, she was a better pony. She knew this in the depths of her heart. She’d found it in the love of both friends and family. She would make them proud. All of them.

It was time for her to take up the mantle for a time. Twilight no longer need stand alone.

Retirement be damned, Luna wasn’t done yet.

The Lunar Princess sucked in a breath and stepped into the circle. Automatically, the magic of the circle ignited, glowing with leftover blueish-black light.

“No!” Luna barked as one would to an unwanted gnat. “You are not welcome!”

Luna’s horn burned and she swept her hands out, obliterating the shadowy remains of Nightmare Moon’s power. The sanctification took only seconds, but she recast the spell several times just to be sure. Only when she was postive the circle had been cleansed did she lift her hands and call out to her charges.

“Beloved Moon, Friend Stars, I ask for your aid!” Luna proclaimed. Despite the crystal, rock and stone between her and the night, there wasn’t a power in creation that could separate her from her charges. “Last I stood here, I sought the darkness, but now I seek your gifts! Please, friends, grant me a portion of your light, so I may protect those we watch!”

The skies trembled at her call. Her charges answered, but not in words. They answered in a song within her heart. They answered with a resounding yes. But they were bound to her as she was to them. They knew her intent and warned her they would not be enough.

Luna had been ready for their answer. Slowly, she began to pull the dress from her body. In a few minutes, it lay on the cold stone as she knelt in the circle. She placed her hands on the cool stone as warm moonlight outlined the intricate patterns and runes.

“Great Heart,” she whispered, letting her power flow into the earth. “I seek your aid as well. I seek not the darkness in your cracks, but the light in your soul. Grant me a piece of your magic to champion your cause once more.”

Another song, another answer, but this one asked for more of her. She did not hesitate.

“Yes.”

Rainbow light bubbled around her hands, affixing them to the earth. The sensation was like unto a warm bath. The same feeling washed over her legs and feet, effectively trapping her. But she refused to panic. This was what she sought. And this was what she had to give. Considering her past, the Heart was wise to be wary.

She may have underestimated how wary.

A beam of rainbow light speared from the center of the circle and through her chest, directly between her breasts. Luna cried out but felt no pain. Warmth radiated from the spear, filling her breasts, her chest, moving down her body meet with the warmth below.

Only then did it slip into her mind.

She gasped as if diving underwater and then blinked.

Then, she saw herself, kneeling in the circle, her expression locked in one of wonder.

“What is this?” No words came out, yet the idea did, even if there was no answer. She looked down at herself to see her eyes wide and filled with rainbow light.

Time passed, though she couldn’t say how much in this strange place as she felt warmth surge inside of her.

Finally, a voice called to her from everywhere.

You are indeed redeemed, but you have yet to accept all truths of yourself. Another trial will be required for you to accept these truths if you are to take our boon.

“I will do whatever’s necessary to protect my land from harm,” Luna thought at the voice.

Of that, we have no doubt. We grant you this but know we will rip it from you if you falter. We shall also grant you a portion for the future. You will know the time. Now, call for your night and let us bind you to your new truth, assuming you pass the last trial.

She blinked and found herself in her own body. The warmth still filled her body, even her most intimate parts. She tried not to shudder at that wonderful sensation as she called her charges to her while kneeling and looking up.

“Aid me in this, my friends!” she cried to the heavens.

The heavens responded with a beam of brilliant white moonlight smashing through the rock and stone, piercing her in the same spot the rainbow light had pierced her. She jerked under her celestial friends' gift, flinging her arms wide with a cry. She felt the warmth and encouragement of both star and stone. Then, she surrendered herself to it and let herself slip away into a swirling maelstrom of rainbows and moonlight.

Author's Note

Ooooooh, this chapter was fun. I don't usually do a ton of worldbuilding stuff (like, except for Spike the... Succubus?), but this was great because it totally could have happened in the show~? Also~? I totes love secret rooms. TOTES LOVE THEM. :3

Lemme know about any mistakes by PM so I can fix 'em~!