Author's Note
This is a pilot that will determine if the rest of the story gets to continue. If it gets a positive reception, there will be more chapters to follow, so I hope y’all like it. 
Part 1: The Discovery
***A Patriot Pony Production***
Spike grumbled under his breath as his feet shuffled across the floor. “Why did I have to come again? Why not bring Starlight? She’s the one who actually likes this kind of stuff.”
Beneath Canterlot Castle, in the fabled ‘Restricted Section’ of the Palace Library, Princess Twilight and her dragon companion sifted through a mountain of books, scrolls, and other documents. To Spike’s dismay, this was no exaggeration, as the reading materials literally towered over them. Twilight, to no pony’s surprise, was loving every second of it.
“Starlight is where I need her to be. She’s making room in our library for some of these lost tomes. Well, they’re not lost anymore, but... You know what I mean.” She fired him a teasing look. “Besides, she’s not my number one assistant, Spike. You are. That means you get to help me sort out which of these babies needs to be added to my collection!”
Spike rolled his eyes and turned his back to the hysterical princess. “Lucky me...”
He loved Twilight more than anything, but he needed some space from the endless sea of heavy novels, and from her obsession with books. Quietly, while she wasn’t looking, he retreated to a more secluded corner of the decayed library. There, he found more of the same, stacks upon stacks of dusty hardbacks and wrinkled parchments, but then, he caught a glimpse of something out of the corner of his gaze.
Half buried beneath a pile of torn scrolls was a small, wooden box. It was the first item of interest he’d seen since they arrived, which was saying a lot. Spike knelt beside the box and uncovered it. Just as he thought, it was a wooden chest, no bigger than a lunch box. A brass latch kept the lid shut, and just above that, engraved into the old, splintered wood, was the letter ‘M’.
Intrigued, he dusted off the lid and opened the latch. The box creaked as it opened. Spike glanced over his shoulder, worried he might have alerted Twilight, but she was still somewhere in her own little world. Spike fully opened the lid, and what he found surprised him.
Inside the mysterious box was nothing more than a single notebook, bound in crimson red leather, and titled ‘Mallory’s Diary’. He opened the leather journal to the first page and began to read.
“Here lies the thoughts and wants of the forgotten princess, Mallory.”
He turned to the next page only to find it blank. In fact, the entire journal was blank. The only words to be found on any page were those he read just pay the cover. Spike figured this Princess Mallory must have been as boring as Twilight if her diary was any indication of her private life. The thought made him chuckle, but the box was still an interesting find.
Without Twilight’s knowledge, he decided to keep it. He placed the journal back inside and closed the lid, sealing the brass latch and placing the box with the rest of the artifacts they were going to take back to Ponyville.
***
A few agonizingly boring hours later, Twilight and Spike left Canterlot to return to Ponyville with their acquired goods in tow. Within the walls of the palace once again, Spike retreated to his bedroom with the box he’d found. He still hadn’t told Twilight about it, though he planned to. If anypony were to know anything at all about the strange diary, it would be the bookworm herself, but he wanted to get a better look at it first.
Spike swiftly entered his room and closed the door behind him before setting the box down on his bed. He lifted the brass latch, opened the lid, and retrieved the leather notebook. “Hmm... Mallory’s Diary...”
He traced a finger over the etched wording on the cover. Then, he flipped the leather front open to the first page, like he had back in the Restricted Section, but what he saw now startled him.
The words had changed entirely.
“To be touched again after so long is a delightful reward for my patience.”
Spike’s stomach churned and twisted itself into knots. He was certain that wasn’t what it had said before, but more than that, the new words came off even more disturbing than the previous line. “What in the...”
He flipped through the rest of the journal to find the rest of the pages were still blank, except for the last one, just before the leather back. There wasn’t a full line or even an entire word, just the letter ‘M’ in the same style as the letter on the lid of the box he found the diary in. Spike’s head was spinning in circles now. No pony could have written in the pages since he last saw them. If only to make sure the ink wasn’t wet, he felt compelled to touch the ‘M’.
Spike let out a deep breath and firmly pressed his thumb into the page, and in response, a sinister fit of laughter echoed throughout the room. He let out a startled cry and dropped the diary onto the floor as the pages began to flip on their own, turning faster and faster until they started to glow red. He wanted to scream for Twilight, but before he could, there was a blinding flash of light that knocked him off of his bed.
Then, there was silence. The sound of rustling pages was gone.
From the floor, Spike could see under the bed and out the other side where the diary now rested. Happy that the ordeal was over, he stood shakily to his feet only to come face to face with a naked mare sitting legs crossed on his bed.
“Hello!”
Spike cried out in terror and fell back on his rear. Following the initial heart attack, he attempted to stand a second time. When he looked at the bed again, he confirmed that his eyes and ears were not deceiving him.
A completely nude mare sat on top of his comforter. Her legs were crossed in front of her, and her arms were resting on her knees, making no effort to cover her voluptuous breasts. Her complexion was pale and bright, and her mane was a mixture of white and crimson stripes with a tail to match. Then, there were her eyes. They seemed unnatural and left Spike feeling uneasy under their gaze.
Spike swallowed hard while trying desperately not to stare. “Wh-Who are you?”
She beamed at him, her devilish grin stretching from ear to ear. “Mallory, the Princess of Lust, at your disservice.”
***To be Continued?***
The staring contest continued to the song of an awkward silence. Spike was utterly speechless in the presence of the otherworldly mare before him, but she seemed to simply be playing along.
From the bed, the mare flexed her shoulders and shifted on her flanks, causing her to sway gently from side to side. Then, she let out an annoyed sigh. “You have questions... I can tell.” She rolled her eyes. “Fine! Go ahead and ask me whatever you wish. I’ll answer truthfully.”
Spike shook his blank stare as if falling out of a trance. “I- Uh... Who are you?”
The mare shot him a frustrated look. “You’ve asked that already...” She closed her eyes and took in a deep breath as if to regain her composure. “I’m Mallory. A few know me as the Princess of Lust and Fertility, but you can just call me Mal.” Her wide grin returned. “What can I call you?”
He’d never heard of such a princess, thought Twilight had notes of other existing Alicorns throughout the world. The mare before him must have been one of them. “I’m Spike.”
Mal looked amused by his name. “Hmm... Well, my dear Spike, I’d say we’re going to be very well acquainted, since you now posses my diary.”
Spike eyed the notebook that was still on the floor, and he reached down to pick it up. “You mean this? You came from this?”
The princess shrugged her shoulders. “In a manner of speaking, yes. I’m actually bound to that little book. I’ll spare you my life’s story, but I was once free to live a life of want and wonder until a certain Princess of the Sun decided to strip me of my wings lock me away from the world.” She turned to show Spike her bare back. The frustrated look on her face passed and was replaced by an eerily cheerful one as she spun back around to face him. “No matter! Wherever my diary goes, I will follow.”
Spike was certain now that he’d never heard of Princess Mallory, but if Celestia had sealed her away, there must have been a good reason.
Mal’s eyes began to wander, shifting from Spike to other points around the room. “Are these... your bed chambers?” Her arms stretched outward as she laid back on the comforter. “I must admit these covers feel very nice to the touch.”
The dragon nodded. “Yeah... This is my room. We’re in the Crystal Palace in Ponyville.”
She sat upright, locking her eyes with Spike’s. “Palace? Ponyville? I don’t remember Ponyville having a palace in it. I must have been away longer than I thought...”
He gestured fo the door behind him. “Sure. This is Princess Twilight’s palace. She’s was made the Princess of Friendship by Celestia a few years ago.”
Mal’s gaze narrowed. “So... Mistriss Sun Butt is still in power, I see.” Then, she closed her eyes and soothed herself with a deep sigh. “No matter. I’m not sore.” Like a switch, her mood apparently flipped again, and she scooted closer to Spike, nearly leaning over the edge of the bed. “Well, now that I’m here, what shall we do?”
Spike was taken off guard by her sudden question. “Do? What are you talking about?”
The white mare’s lips curled into a smile. “You possess my diary, remember? That means you possess me as well. I’m the master of lust, so I’m game for pretty much everything. If there’s a kink, I’ve got it.”
It finally dawned on Spike just what she was insinuating. “Wa-Wait, slow down... I don’t want to- You can’t just come in here and demand that we...” His voice trailed away as his voice failed him.
Mal quickly shook her head. “Okay, I think we’re getting off on the wrong foot. Spike, I’m here to serve you, not the other way around. As long as my diary is yours, I’m yours. Get it? If you don’t want to have sex with the Princess of Lust and Fertility, that’s your deal. That, however, doesn’t break our contract.”
Spike felt a sense of relief wash over him. “I’m sorry... This is a lot to wrap my head around, and... Well, you’re a bit distracting...”
The princess looked down and observed her own naked form. “Oh? So I am...” With a snap of her fingers, she was wearing a thin blouse that covered her chest and flowed down her legs to form a skirt at her knees. “You must understand that it’s been quite a while since I’ve been summoned by a mortal. There’s no need for clothes in the diary.”
Spike began to wonder what exactly it was that Mal did to get herself sealed away like that. Angering Princess Celestia wasn’t easy, so it must have been bad. Whatever the cause, however, he thought it better not to bring it up with Mal, as it seemed like a touchy subject. Then, an idea came to him like a scream in the night. This must be his chance to reform her! He figured if that could be done, he could even free her from the diary.
He cleared his throat. “Ehem... Okay, Mallory. I’ll do it.”
With wide eyes, she began lifting her blouse. “You mean you want to have sex now?”
Spike quickly shook his head. “No, not that! I mean I’ll go along with this, letting you stay here.”
Mal beamed at him. “Wonderful! I have no doubts that you’ll take good care of my diary.” She began to giggle and squirm. “Oh, this is so exciting! It’s been centuries since I’ve had a roommate. I hope you don’t mind if I take this side of the bed. I prefer the view of the window.” That wasn’t what he meant at all, but before Spike could object, she burst out laughing. “Ha! The look on your face... I’m teasing you, my sensitive dragon. When I’m not needed, I’ll be in my diary, so you’ll always know where to find me.”
Then, in a flash of light, she vanished.
He let out deep breath. The task of reforming her could have been harder than he originally thought. Then again, he didn’t even know where to begin, because he didn’t know what she didn’t to have herself trapped in a journal in the first place. Then, there was the problem of Twilight finding out. He couldn’t even begin to imagine what she might have to say about all of this.
Spike looked down at the dairy in his hands. It suddenly felt heavier than it had before. Out of curiosity, he opened the cover to the first page to discover that the line had changed again.
“If you have need of me, all you need do is ask. Until next time, my dear Spike.”
***Up Next: The Bargain***