“Sunset, you’ve got to help me!”

Sunset Shimmer turned her head towards Twilight Sparkle, giving her friend a curious look. Twilight looked distressed, upset, and as though she had been fighting. She was sweaty and scorched in a few places.

“What’s going on?” asked Sunset Shimmer in a low voice as she tried to remember what she was doing here. Thinking about it made her head hurt and her ears pinned back against her skull. The unicorn winced as her vision blurred and tripled over.

“It’s Bucky… he’s slipped into darkness… he just started cackling and he’s lost his mind.” Twilight shook her head. “He’s gone on a rampage!”

Sunset Shimmer considered Twilight Sparkle’s words. Sunset was Bucky’s apprentice, she was supposed to be loyal to him above all else. In the distance, she heard an explosion, and everything around her shook and rumbled. She owed Bucky everything. He had given her a home, because of him, she had Bartleby and Trixie. Because of him, she was back in Equestria and she had magic again. She bit down upon her lip, hesitating, preparing herself for what she was about to do.

“Twilight, let’s go take him down… but let’s see if we can do so without killing him…”

The moon was high in the sky, blocking out the sun in an eclipse. Something felt off, but every time that Bucky tried to reason out what it was, a stabbing pain shot through his head. It was almost as if something didn’t want him thinking about it, which was a cause for alarm, but when he thought about that, he was punished with pain.

“Buckminster…”

His ears perking, Bucky could hear that Celestia sounded heartbroken. He looked at her. In the dim light, he could see her red, bloodshot eyes. Her cheeks were stained with tears. She looked disheveled, which was not a natural state of affairs for Celestia, who almost always looked immaculate.

“Buckminster, Luna has once again succumbed to her inner darkness… help me!”

Hearing Celestia’s words caused Bucky no end of pain. Luna, his Mistress. Luna, the one he had made a deal with. He had given himself over to her, offering his service, his loyalty, and his dedication. In return, Luna had given him power. Luna had allowed him to keep his family. Luna had been good to him. He owed Luna. He would serve her without question.

“Bucky, please, Nightmare Moon has once more reclaimed my sister!”

He owed Luna, not Nightmare Moon. He looked up at Celestia and then heard horrible, cackling laughter, the laugh of utter lunacy. He hung his head as he made his decision.

Looking defeated, he walked to Nightmare Moon’s side, his head low, looking submissive. As he walked, he heard Celestia say, “How could you?” It stabbed at his heart, but he had his reasons. He wished more than anything that Celestia would trust him, but he understood. Reaching Nightmare Moon’s side, he angled his head upwards to glance at her. She was laughing even harder now, revelling in her sister’s misfortune. There were no shields, no defenses, Nightmare Moon had done nothing to defend herself.

“You took my teacher away from me,” Bucky hissed as his horn charged up. There was a flare of blue-green light as Bucky unloaded everything he had, slamming into Nightmare Moon in a devastating sneak attack. The world around him filled with sunlight and Bucky was blinded…

Disoriented and confused, Sunset Shimmer looked around. She was in a small room. Blinking, she tried to remember what had just happened and couldn’t. She remembered stepping through a mirror… and then, nothing. Now she was here and Bucky was beside her, still as a statue. She saw one of his ears twitch and then, he started moving. She heard a faint grunt.

The room was small and there was a familiar looking staircase at one end, the stairs they had just spent what felt like hours going down and up, until figuring out what to do. The room seemed nice enough. There was a little couch, a table, a light globe that hung from the ceiling, and another door.

“I don’t remember anything.”

Sunset Shimmer nodded. “I have the same problem. I wonder what just happened?”

“Minion, I suspect that we were tested somehow.” Bucky shook his head, causing his ears to flop around. His horn glowed with a piercing light. Two cups made of ice appeared and with a splash, they were filled with water. “Care for a drink?”

“Why thank you, Master, you are so thoughtful,” Sunset Shimmer replied as she accepted the cup. Tilting back her head, she took a drink, not realising how thirsty she was until the icy water hit her dry, parched throat. She swallowed and smacked her lips. “Well, we have new hats and we figured out the staircase of infinite doom. I wonder what is next?”

“There is the door right over there. We’re about to find out,” Bucky replied.

Much to Bucky’s surprise, the door opened without difficulty or test. Beyond was another room, something that Bucky was not surprised about. This room was filled with doors. Four doors, to be exact. The first door had a snowflake, the second door had a sun, the third door had a seven pointed star, and the fourth door had a moon. There was nothing else in the room. Nothing at all. No warning, no hints of what lie beyond the doors, there wasn’t even a rug on the floor.

“Oh great.” Sunset Shimmer shook her head and then, reaching up, she pushed her hat back upon her brow.

“I have no memories here,” Bucky said as he stared at the door with the moon upon it.

“I’ll open the snowflake—”

“Minion, the snowflake is clearly intended to be mine!”

“But I called it…” Sunset Shimmer gave Bucky a sour look, squinting one eye and curling her lip back as she glared at him.

“Oh, very well, you may have it.” Bucky gave his talons a dismissive wave. He watched as Sunset Shimmer went to the door to open it. Nothing happened. He could see her magic around the door handle, tugging on the latch, but the door did not open.

Reaching out with his mind, he gave the door a tug. Nothing happened. Confused, Bucky blinked a few times and then tried both pulling and pushing upon the door. It did not budge. It didn’t even wiggle.

Sunset Shimmer sat down upon the stone floor and let out a frustrated huff. She tried pulling on the other doors, and each door remained unmoving, until at last, the frustrated unicorn mare gave up. She looked at Bucky and asked, “Any ideas?”

There was no reply as Bucky stared at the doors, his brows furrowed, and his lips pressed into a straight line. He stared at the door with the sun, wondering if perhaps Celestia was needed to open it. He looked at Sunset Shimmer and thought about her cutie mark, the balanced sun.

No, Bucky reasoned to himself. Celestia was not needed to open these doors. Bucky’s logic told him that if she or Luna were needed to open these doors, then the letter would have said so. He and Sunset would be able to open these doors somehow.

“Sunset, about your light spell…”

“What about it?” Sunset Shimmer looked away from the doors and looked at Bucky instead. She could see that Bucky had that look on his face when he was about to do something clever.

“Is it true light? Does it have ultraviolet radiation?” Bucky asked.

“No.” Sunset Shimmer shook her head. “I don’t think it does, anyway.”

“Well, cover your eyes. I’m about to try a test.” Bucky’s horn glowed and he squeezed his eyes shut. He pulled his hood around his face, trying to shield himself from what he was about to do.

His horn protruded from his hood and Bucky focused his magical might. It was difficult to call this magic up. His body had become so attuned with shadow that he wasn’t certain that this would even work. A strange pain filled his head and there was an odd tingling that Bucky felt in his horn, an unpleasant feeling.

A beam of light shot from the tip of Bucky’s horn and hit the door. There was a loud, clarion trumpeting blast, the whole room shook, and then, as Sunset Shimmer watched through squinted eyes, the door vanished.

Seeing that the door was now gone, Sunset Shimmer understood the doors. The first door was to generate actual sunlight, from the bloodlines of ancient unicorn royalty. While Sunset knew that she descended from both Star Swirl and Sombra’s bloodlines, she didn’t seem to have whatever it was that made certain light spells have sun magic. She looked at the other doors. The moon door would be dream magic or shadow magic. She supposed that Bucky had that covered. The ice door would also be openable by Bucky. The third door was a star. Sunset wasn’t certain what it was, but she supposed that there was some kind of magical lock on it that Bucky would be able to open. Thinking about this made Sunset feel rather useless and she sighed a despondent sigh.

As she sat there watching, Bucky hit the moon door with shadow magic. Much as she suspected, it vanished. The temperature plummeted as Bucky blasted the snowflake door with entropic ice. The door vanished, leaving only the door with the star.

“The last door should be some form of regular magic,” Bucky said as he fired a pulse of magic at the door.

Blinking, Sunset Shimmer realised that nothing happened. She watched as Bucky hit the door again and again, and with each blast, nothing happened. Reaching out, she touched Bucky to make him stop as she had a revelation.

“Master, these doors were here for a reason,” Sunset said in a soft voice. “Master, I know what opens the last door… Twilight Sparkle should have been here, this is her door. She would have been the key.”

“What do you mean, Minion?” Bucky looked at Sunset with one eyebrow raised.

“Twilight Sparkle taught me that friendship really is magic,” Sunset replied as she brushed up against Bucky. “Star Swirl, being able to see ahead the way that he did, probably knew that Twilight would be able to open this door with a magic unique to her. But, since he knew that Twilight wasn’t going to make this trip when he sent that message, it means that I can open it as well.” Sunset Shimmer bowed her head.

Feeling Bucky beside her, Sunset Shimmer thought of the warm feelings she had for him. She thought of her friends on both sides of the mirror. She thought of Bartleby and of Trixie. She thought of Twilight. She thought of Celestia… and of Celestia’s forgiveness. Sunset Shimmer lifted her head. “I am the key.”

Walking forwards, Sunset Shimmer went to the door, the only door remaining. She lowered her head and touched the tip of her horn to the door. With a trumpeting sound and a flash of light, the door vanished and then, so did the room.

When Sunset Shimmer saw the demoness, she almost screamed. It looked so very much like how she had been. Humanoid, in a vague sort of way. But then, she realised that while it was similar, it was also very different. It had four legs and four arms. Enormous bat-like wings sprouted from her back. She had horns and there were four pairs of eyes. The demoness was also wearing glasses.

“Greetings,” the demoness said in a soft voice. She bowed her head and then raised her arms. “I suppose you have questions. My name is Hex Libris.”

“I suppose that you mean us no harm,” Bucky said, stepping forward and in front of Sunset, his head high. He narrowed his eyes at the demoness. “Tell me, why should I trust you?”

“Because I gave my word to preserve this place and be its caretaker.” Hex Libris smiled, revealing an odd collection of teeth. “I swore a solemn oath to both Star Swirl and Sombra to look after this tower.”

A faint memory trickled into Bucky’s brain, it tickled as it manifested. Details began to emerge. “Yes… I came to you… I found you in Tartarus… you were bound, the prisoner of another… I took pity upon you because you were not like the others.”

“Yes Master, this is true.” The demoness bowed again.

Sunset, hearing this exchange, felt her blood run cold. She looked at the demoness, peering out from behind Bucky. Burning curiousity filled Sunset Shimmer’s mind and she wanted to know more. She wondered how much of Sombra was inside of Bucky’s mind.

“You… your magic powered the tests. You kept this place during my absence. You preserve the Well of Knowledge… I remember now… my brother and I offered you refuge and an endless number of books to read in exchange for your eternal service.” Bucky spoke with a voice not entirely his own. It was almost as though two ponies were speaking out of Bucky’s mouth.

“Yes Master.” Hex Libris bowed once more and then began to walk towards Bucky.

“Well of Knowledge?” Sunset Shimmer asked.

The demoness, now standing near Bucky, made a come hither motion with one of her many hands. She began to head towards a door. Sunset Shimmer, overcome by curiousity, followed after the demoness, and Bucky followed after them both.

“My brother wanted knowledge more than anything else… he wanted books… he wanted learning. He found a way to have access to every book ever written… strong magic… a means to replicate every book ever written within this realm and within the realms connected directly to this one, plus all of the nearby mirror dimensions. An endless stream of books, copies of every book in existence… and all he needed was the heart of a demon to power the magic… we found Hex Libris—”

“And you gave me refuge in exchange for my powerful magic,’ Hex Libris said, finishing Bucky’s words. “I power the magic required for the Well of Knowledge and I get to read endlessly.” Hex Libris walked through the door and made a gesture, causing the lights to come on.

Sunset Shimmer, passing through the door, took a few steps and froze. Before her was a railing that went around a hole. Angling her head, she looked down and saw a hole that had no visible bottom, something that appeared to stretch on forever. Sunset was no stranger to extradimensional spaces, but this, nothing in her whole life could have prepared her for this. It was nothing but bookshelves all the way down, in what appeared to be a bottomless hole.

“Below us is a copy of every book written in this reality and those immediately surrounding it. Books of knowledge, books of learning, books for leisure.” The demoness spread her wings, took to the air, and hovered over the extradimensional hole. “Star Swirl brought back books from his early mirror travels. He realised that other whens and wheres had information that he wanted. He created a system that would give him access to those books.”

“I created the powerful enchantments that would draw up a copy of the book.” Bucky peered down into the hole, a strange expression upon his face. “When last I saw this, it was not this big. So much has changed in a thousand years. So many more books. Learning and education have grown considerably.”

“I am dreadfully behind in my reading list,” Hex Libris said as a smirking smile spread over her lips.

“Why would a demon choose this life?” Sunset Shimmer asked.

“Not all demons are evil,” Bucky replied, still speaking in two voices.

“I am a spirit of knowledge. I have no desire to bring harm to others or to torment the souls of the damned. I was captured by a demon lord who used me and my powers of divination for his own twisted ends. The brothers rescued me and I willingly dedicated myself to their service.” The demoness spread her many arms. “Look at this place. I have everything I will ever need here, including safety.”

“So this tower is ours now? Did we pass the tests?” Sunset Shimmer asked as she tried to take in everything around her and failed. It was overwhelming. She sat down upon the floor, her eyes wide, and stared.

“You have passed the tests. This tower is yours. I have already began to restore functions to make this tower comfortable for the living. The ancient rooms are waking up and soon, everything will be operational.”

“Twilight Sparkle is to be given authority over this tower. She is of Star Swirl’s lineage and she will be the Master of this place. I ask that you obey her,” Bucky said to Hex Libris.

“I cannot wait to meet her, I adore her writings and her many books. I have read them all… I am a huge fan and eagerly await the times when a new book appears.” Flapping, the demoness flew over to where Bucky was and landed. She folded her wings and then dropped in a low bow. “I will do as you ask. You have reclaimed this tower, it is yours, but you may name another Master to act in your stead. I will obey, as I am bound to my contract.”

“Don’t you want to be free?” Sunset Shimmer asked. “I dunno that I like that you are bound by a contract. Doesn’t your freedom mean something to you?”

“But I am free!” Hex turned to look at the confused unicorn mare. “This is a servitude of my choosing. I offer up a portion of my magic to power this place, and in return, I get my heart’s desire. This is a fair exchange. Here, I am not molested nor am I coerced into unsavoury acts that rob me of my dignity. This place is my sanctuary. This is my home.”

“I’m sorry, I just feel funny about this.” Sunset Shimmer looked at Bucky, hoping that he would say something that would make her feel better, but Bucky was now looking at the many books below him.

“You chose voluntary service to Buckminster. You willingly call him Master. Do you feel diminished or somehow reduced to a state of slavery?” Hex Libris asked.

“Well… no,” Sunset replied. She shook her head. “As for calling him Master, that’s more of a title of affection than anything else. He is my teacher… I am not his slave, I am his equal and I know that. He has never made me feel servile or lesser.” Sunset reflected upon the nature of her relationship with Bucky, feeling very, very confused. “Could you end your contract and leave this place if you wanted to?”

“Why would I want to?” The demoness pulled off her glasses, blew on them, and then put them on her face, adjusting them so that each of the eight lenses covered each of her eight eyes.

Sunset Shimmer realised that she had no understanding of demons in spite of almost becoming one.

“I sense the presence of Princess Luna.” Hex smiled at Bucky. “Should I invite her down? It has been so very long since I have seen her last.”

“Oh yes… that might be a good idea,” Bucky replied, sounding a bit more like his usual self and speaking with one singular voice. “If you will excuse me, I just remembered where the wine cellar is. I am off to get reacquainted with some old friends.”

“Master, wait, I think I would like a good, strong drink! I am coming with you!”

Author's Notes:

We may never see Twilight Sparkle ever again.