Darkly Dreaming Derpy:

Obviously I do not own the rights to the Dexter series (if I did then you can bet the terrible T.V. series would not exist), nor do I own My Little Pony (otherwise the third season would not exist), and I am in no way trying to pass of either of these unique properties as my own brainchild. Oh, and sorry but Derpy is not actually in this story, but the title was too appropriate to not use.

Chapter One:

The last thing Twilight Sparkle remembered was attending a memorial banquet. It had been five years since she had taken on the mantle of Queen of Equestria, and since then journalist ponies have been hounding her for the rights to her biography. A life filled with tragedy makes for gripping reading, and the deaths of Twilight's closest friends certainly qualifies.

At this particular banquet, a journalist by the name of Steppenhooves was unrelenting in his pursuit of Twilight, which resulted in her secreting herself out the servants' exit at the back of Canterlot's castle.

Twilight only intended to be out for a few minutes to regain her composure, maybe chew a little tobacco to calm her nerves (a disgusting habit she'd taken up since assuming control over the governance of all Equestria). What Twilight had not counted on was the assailant hiding behind the rubbish bins. Without being afforded a single moment to perform some defensive magic, Twilight received a sharp crack to the back of the head that quickly sent her to the land of nod, where she dreamed the dreams of the recently concussed.

When Twilight eventually awoke, she felt uncharacteristically cold. Groggily she tried to move her head, only to find it an impossible feat. Further exploration revealed that any movement save for her eyes was also impossible. Beads of sweat formed on her brow as she tried to clear the cotton wool from her mind and summon some magic, any magic, but to no avail. Somehow her head felt...different. Lighter maybe? But she quickly discarded this idea as it seemed unproductive. It wasn't until Twilight tried to vocalize her concern that she realized she was gagged. The large wooden bit secured in Twilight's mouth meant she was not saying anything anytime soon.

So preoccupied was Twilight with her predicament that she failed to notice the brunette unicorn busying himself with what appeared to be photographs.

Chapter Two:

The dark rider was getting eager now. It had been too long since he had taken the reigns, and his excitement neatly mirrored my own. It had scarcely been a year since I was untimely ripped from Miami and found myself in a strange land. I still remember the day. I was driving to a murder scene to offer my dearest sister Debbie help with the investigation, when I suddenly found time and space warping around me. This was disconcerting to be sure, but I like to believe that I kept my composure. After all, such unbelievable events serve to destroy the very fabric of one's perception of reality...provided one clings to the security blanket of one's humanity. Fortunately for me, I suffered no such delusions about my humanity, and the whole event was only mildly disconcerting. Something that I will admit was unpleasantly weird was the place I ended up. I found myself in the body of what appeared to be a pony, in a land of anthropomorphic ponies. It only took me a few days to fully take stock of my situation. I was now a unicorn, which was handy considering that my newly acquired horn magic more than made up for my lack of hands. Upon my flank was a tattoo of a scalpel. This was another lucky stroke as I learnt that these "cutie marks" represent the defining characteristics of each pony. All things considered, I could have ended up with a bloodstain or some other gaudy and incriminating symbol. As it stood, I was just a short trip to the library away from forging my new identity. Within three days of being dropped in a strange and foreign land, I went from Dexter Morgan, the deadly and dashing expert in blood splatter pattern analysis, to Dexter Morgan, the mild mannered slashing surgeon from the faraway Shetlands (I still cringe at this world's preoccupation with horse puns), who has recently started up a modest little practice in Ponyville.

However there was something about Equestria. Everyone (or perhaps I should get used to saying everypony) was so...nice and whimsical. No-pony seemed to fit the criteria for a target in the Harry code. A few months of this pushed me in the general direction of depression, but I did not become despondent. If there was one thing that I knew with certainty, it's that appearances can be deceiving. My whole dark hobby was built on the foundation of putting a friendly and unassuming face on my terrible deeds. I just had to dig until I found a worthy target. And it was during one of my regular research sessions in the library that I found a monster that Equestria could do without. And with that happy discovery, I set out to begin the long and glorious process of preparing for the kill.

Chapter Three:

After a while, Twilight had regained some composure as the strange unicorn removed her bit.

"Wh-what's going on here?" demanded Twilight, cursing herself for her quavering voice.

"Well, some might call it karma or divine retribution, but I think you and I know a little better don't you?"

"What are you talking about? What are you going to do to me?"

"Nothing you or I haven't done many times before. Nothing you don't deserve."

"I don't know what you are talking about, but I do not much care. Do you really think you can stand against the power of the Elements of Harmony?"

"Yes, I was rather worried about that. Ever since you gained control of all the Elements of Harmony you've been quite formidable. How did you come by them again? I understand that your friends used to possess them. What happened to them?"

"They...they passed on." muttered Twilight, a single tear running down her cheek. Twilight elected not to answer the other questions. She did not wish to revisit the arcane ritual she had to perform to assume control over the other Elements, nor did she want to admit to anypony (herself included) that she had never had a chance to test out her control of the other Elements.

It was at this point that Dexter reached for one of the photos and held it in front of Twilight's face.

"Yes, like poor Applejack. Ate a cursed apple from the Everfree forest unless I'm much mistaken."

"Look, this is very painful for me. Please stop this."

"As painful as Rainbowdash's mountain accident?" inquired the unicorn as he reached for another photo.

"There wa-was a lot of cloud cover. Sh-sh-she never saw the mountain until it was too late."

"So you say. Just as you claim Fluttershy was trampled to death by her menagerie? I have to say that you were getting downright sloppy at this point."

"I don't know what you are talking about! Release me this instant!"

"Such a demanding tone. Not unlike Rarity if what I've been told is true. She supposedly tripped and impaled herself on her sewing shears. Like I said, sloppy. You wouldn't last a single day in Miami." he said as he showed Twilight the horrendous picture from the crime scene files that he procured from the CPD's (Canterlot Police Department) archive.

"Don't you mean Mareami? You look more like a Shetlander to me." remarked Twilight with an air of forced levity.

"Whatever. Now where were we? Ah yes, Pinkiepie-"

"Stop! Please! Why are you doing this?"

"That's enough of the blubbering. I'm not afraid to fetch the bit and continue this little presentation unimpeded. Like I was saying, Pinkiepie. Drug overdose? I could almost believe that one. Apparently her parties took on a near suicidal intensity after Rainbowdash bit the big one. I guess everypony grieves differently."

"Why are you doing this?" pleaded a desperate Twilight, the tears freely flowing now, all pretense of composure forgotten.

"Aren't you proud? Proud of your work? I'm sure you're proud of your first little project."

And with that Dexter placed the last photo in Twilight's line of sight. Twilight shut her eyes in anguish, and tried to force her head free of its bindings. But no sooner had she retreated into the safety of the darkness behind her eyelids that she felt them being forced open by the unicorn's magic.

"You're not getting out of this that easily. I need you to see this."

Left with little choice, Twilight was faced with a portrait of princess Celestia and her sister, Luna.

"I would never touch them! I am haunted by their death's to this day. Celestia was a mentor to me!"

"I'm inclined to believe you, your majesty, but all the evidence points in your direction. You've coasted by on the ineptness of your nation's pathetic police force for too long. The official report claims that Luna went mad and attacked Celestia, resulting in the two Alicorns lethally stabbing each other. Fortunately for Equestria, this loss was tempered slightly with you being crowned as the new Queen-"

"Enough!" exclaimed Twilight with a voice like the echo of an ancient divine battle cry, her eyes aglow with power. "You have gone too far! Prepare to taste my wrath!"

Dexter appeared unimpressed by the display, and nothing followed the proclamation.

"What happened to my magic?"

"I was getting to that. Like I was saying, the stab wounds on the two Alicorns did not match up with each others' horns. But after a few minutes with a hacksaw, I found a horn that matched the dimensions of both stab wounds. Does this look familiar?"

There was no doubt in Twilight's mind that the horn being brandished by her captor was her own.

"You monster! I'll get you for this! I still have the other elements! I can still use them to destroy you!"

"Well let's review your situation. You've lost your magic. Your loyalty was destroyed the day you started killing your friends. You've lied every day you failed to admit to your deeds. You have long ago discarded any pretense of kindness, and you are in no position to show anypony generosity right now. I'm the only pony here and there is nothing that you can give me that I need or want. So now I have just one thing to ask you: let's hear you laugh."

This prompted Twilight to scream wildly.

"I'm afraid you are wasting your breath. I've worked hard to ensure that no-pony interrupts my fun. We're quite far from the rest of pony kind, and when I'm done with you, you'll be a neatly wrapped package buried deep in the Everfree forest, and a smear of blood on a glass slide in my new collection. Which reminds me..."

As Dexter advanced upon his captive, he picked up both a clean scalpel and a fresh glass slide. With a practiced motion , Dexter nicked Twilight's left cheek, creating a small welling of the wet sticky icky. The sight of the stuff both disgusted and excited Dexter, and he could barely contain himself as he applied the glass slide to the wound and placed it in a small rosewood box.

"Funny, I was half expecting silver blood. I guess that's what I get for watching those Harry Potter movies."

"Wa-wait. Pl-pl-please don't do th-this. I ju-ju-just wa-wa-wanted to st-step out of Celestia's sha-sha-shadow. Sh-she never sa-sa-saw me as mo-more than a s-s-student. And after I k-k-killed he-her, I couldn't st-stop."

"Oh, it's okay. You can stop talking now. I've heard what I wanted to hear, and now the fun begins."

"But think of Equest-" Screamed Twilight, only to have her plea cut short by the gigantic bit being fixed to her mouth. Once secure, Dexter moved out of her line of sight, leaned close to her from behind the table to which she was secured, and whispered in her ear "Goodbye Twilight. This will be the last time we see each other. Unless, of course, I've been wrong all this time and there actually is a Hell." And with that Dexter set about his business.

Epilogue:

As Dexter showered away any evidence that may remain about his person, a feeling resembling guilt twinged in his gut. At least he thought it was guilt. He had read about it once and this seemed to fit the description. "Killing a unicorn? That has got to be a new low." mused Dexter with a slight smile as he shut off the shower's valve and set out to find breakfast.