An almost-gentle slap to the face woke Twilight. A voice said, “Hey Sparks, get up.”

Opening her eyes revealed an alien face inches from her own. She squeaked and tried to recoil in horror, but lying on her back in bed left few options for escape.

The strange creature rolled its eyes and straightened up, calling out, “Heads up, it’s another Twilight day!”

A few other voices from somewhere else expressed their displeasure. Twilight sat up. “Who are you?”

“I’m Thomas. Your name is Sparks. You volunteered for an experimental program to enhance Marine combat effectiveness with the ability to use magic and to survive on nothing but grass. It had the side effect of turning you into a purple unicorn mare who occasionally thinks her name is Twilight Sparkle.” Thomas sighed as if he’d explained this before.

“I’m…sorry?” Twilight looked down at herself. Other than wearing slightly more clothing than normal, it looked like her usual body.

Thomas turned. “You said you wanted to go to breakfast this morning. I was just waking you up so you aren’t late.”

Twilight had no idea what he was talking about. Maybe she should ask more questions. She slid out of the bed to follow Thomas as he went out the door. Her legs were wobbly and the movement brought to her attention a headache she hadn’t noticed until then.

Am I hungover? Her mouth felt dry. Twilight lifted the curtains, her magic wavering just a little. She quickly squeezed her eyes shut at the glare of the sun. Turning back to the room, she stepped around some clothing on the floor. It was sized much smaller than the items Thomas wore, so it was probably hers.

Twilight wore thin, tall stockings on her back hooves for some reason. There was also a piece of fabric that ran between her legs and held snugly to her hips. It was not uncomfortable, so she decided to leave it on for the moment.

She poked her head out the door, glancing left and right down a hallway. Another of the creatures she shared the space with stepped out of a door. “Morning, Sparks.” He stopped. “I know you’ve got the whole different species thing going on, but could you wear more than just panties around the apartment? Some people, like my girlfriend, don’t approve.”

“Uh, sure.” Twilight nodded.

“Oh right, you drank Killian’s last night so it’s a Twilight day and you don’t remember me.” He nodded. “My name’s Jacobs.”

“Pleased to meet you.” Jacobs thought that was funny for some reason. He chuckled and walked away.

Twilight retreated back into the room she’d woken up in. She picked up the clothing scattered around, putting it in a basket filled with other rumpled clothes. Inspecting the wardrobe revealed several different kinds of uniforms, probably military. There was also plenty of other clothing that resembled what Thomas and Jacobs wore.

Twilight picked out an outfit, which according to the individual tags on each piece of clothing consisted of a “T-shirt” and “jean shorts.” Before putting it on, however, she thought it best to have a shower. There was a towel hanging on a hook, and the bathroom was right across the hallway.

Passing by the mirror, Twilight stopped short. Her mane and tail were cut much shorter than normal, although still longer than the other creatures she had seen. What had Jacobs called them, people? She shook her head and quietly resolved to take things one at a time. It was difficult to turn off her inquisitive attitude.

Refreshed after showering, Twilight returned to the bedroom. She still was not sure what purpose these so-called panties might serve, but put on a pair beneath the other clothes.

She stepped into the hallway, watching Thomas pounding on another bedroom door. “Gintrowski! Get up! It’s a Twilight day.”

There was a muffled groan and after a few moments the door opened. A face looked out, glancing at Twilight and nodding. “Sure enough.”

“You can tell it’s me just by looking?” she asked.

Thomas nodded. “Sparks walks on two legs.”

Gintrowski groaned again and muttered, “Jeeze, you’d think the Polish name would help me at least a little with the beer.”

“Polish?” asked Twilight.

“The universal law of Polish surnames,” said Thomas. “As a group of people grows larger, the odds become greater that someone will be named –ski. It’s statistical probability.”

“I like statistics,” said Twilight.

Gintrowski and Thomas shared a knowing look. Jacobs came along just then. “Let’s go to breakfast.”

They left the apartment and got into a contraption with wheels. Twilight’s assumption of a vehicle proved to be correct when Gintrowski put in a key and brought the machinery to life. A few glowing numbers on the dashboard seemed to indicate time. It was 10:36.

“So you—we, I guess—are in the military?” asked Twilight.

“We have got to get her to start asking different questions,” whined Jacobs. “But yes, the four of us are members of the United States Marine Corps. We're technically a part of the Navy and sometimes ride around on their ships, but truthfully we're the most badass fighting force in the world, we know it, we'll tell everyone who will listen, and skullfuck the ones who don't.” The others nodded in agreement, murmoring something that sounded like oorah.

Twilight swallowed hard, unsure what she might be getting into. “So if we’re in the military, why are we wearing civilian clothes and going to breakfast at midmorning?”

“It’s Memorial Day Weekend. We’re on a 96-hour pass. That’s the only reason we let Sparks have Killian’s,” said Thomas.

“I still think we should do it more often,” muttered Gintrowski. “Sparks is starting to creep me out.”

“I understand the shock of being turned female, but yeah,” agreed Jacobs. “Stockings and short skirts are not what I want to see my buddies wearing. If anyone actually wanted to tap that flank, I wouldn't let Sparks use the apartment.”

“That’s another thing I like about you, Twilight, you don’t dress like a hooker,” laughed Thomas.

“I’m sorry, I don’t really remember anything about switching places,” said the unicorn.

Jacobs looked apologetic. “You never do, Twilight. Sorry, but Sparks is the dominant personality. The shrinks have given up trying to explain it.”

That was a worrying thought. Twilight could remember her life in Equestria. Surely she wasn’t just a figment from the imagination of the mysterious Sparks?

In another few minutes, the four of them arrived at a restaurant. Inside, the chairs were a little uncomfortable for Twilight to sit on, but she managed to do a reasonable impersonation of a person.

“What do I like to eat?” she asked. It seemed like a silly question.

“They say you’re an herbivore, but Sparks never had any trouble digesting a few strips of bacon,” said Gintrowski.

Twilight did not like the connotations of his statement, but let the three of them order for her. None of the wait staff or other customers thought it odd that a purple pony was among them. Perhaps Sparks was a regular.

The food was good. Scrambled eggs and toast were the only recognizable parts, however. Twilight mostly kept quiet, listening. She was able to piece together a surprising amount of information just by keeping an ear on the breakfast conversation. It helped her take her mind off whatever the mysterious bacon might be made of. It was too suspicious to put out of her mind, but too good to stop eating.

It still wasn’t quite noon when they left the restaurant. Jacobs asked, “So what do you guys want to do?”

“Go to a movie?”

“Jarhead’s playing.”

“We’ve seen that like fifteen times.”

“Do you care?”

“…No.”

And so Twilight was introduced to the cinematic experience that was Jarhead. Creating quite an impression on her were the masturbation discussions, general attitude, and the 278 mentions of the word “fuck” over the course of the two-hour film.

Exiting the theater, Twilight commented, “Is that really how the Marine Corps is?”

“It can be,” said Jacobs. “It can suck a lot.”

“On the other hand, you don't look anything like Jake Gyllenhaal, so we're probably safe,” added Gintrowski.

Twilight frowned, trying to remember which character that was. “I’m not sure what to think.”

Thomas grinned. “It’s two o’clock on Saturday afternoon. You don’t think, you drink.”

And so they did. They found a local drinking establishment and entered. The walls were covered with Marine memorabilia. Twilight looked around, feeling a little hesitant, but found that a few beverages helped her relax. The four of them were soon gathered around a table, talking and laughing. The pony mostly sat and listened, occasionally sipping beer. Once in a while she broke in with questions.

“So what made the military decide to turn someone into a pony?” she asked.

“There are a lot of advantages,” said Jacobs. “You’re a little bit smaller target now.”

Gintrowski commented, “The repeal of Don't Ask Don't Tell now allows same-sex couples, but nobody said anything about same-species."

“The fur gives you a little insulation, which helps in cold climates, but also stops hot brass from burning your skin,” added Thomas.

“5.56 millimeter hickey,” laughed Jacobs.

“Technically it’s hair, not fur,” corrected Twilight. “What is 5.56 millimeter?”

“Ammo,” said Thomas. He smiled. “One of these days, we need to take Twilight to the shooting range.” There was a general chorus of agreement.

As the afternoon wore on, more people entered the tavern, the vast majority of them Marines. Before too long, it was a party. As most of the attendees were drunk young men, it was quite a wild one. Twilight could feel her self control slipping away with every sip, and was not sure she cared. After all, if this was her day to take over, why not have some fun? It would be Sparks paying for it, just like she’d woken up that morning with his hangover.

A bottle of something was brought to the table along with shot glasses. Twilight amused herself and the other three with a bit of magical trick pouring.

In the background, the noise of the crowd only increased and somewhere loud music was playing. More alcohol fueled the festivities, and everywhere Twilight looked the throng of people appeared to be having a good time.

And then the branding started. Someone had brought a small propane torch and a metal form with the letters USMC on it. A couple of eager Marines wished to get a permanent marking of their time in the Corps.

“You should go do that,” said Jacobs, slurring his words a little. “Maybe getting your ass branded would keep Sparks from wearing skirts so short.”

“But I like my cutie mark,” protested Twilight.

“Can you heal it with magic?” asked Gintrowski.

“I suppose.”

“Well, leave the brand for Sparks to find. He’ll freak, and then you can take care of it the next time you come back.”

Twilight grabbed the bottle, bypassing the shot glass in favor of a swig. She giggled. “Let's do this.”

Her three buddies escorted the pony over to where the branding was going on. She dropped her shorts and presented her posterior.

Twilight snapped awake with a little shriek. She looked around at the bedroom’s wooden walls and her dragon assistant Spike in his own bed nearby.

“Huh? Twilight, what's going on?”

The unicorn moaned and lay back. “That dream again, Spike.”

“You really shouldn't have volunteered for that learning experiment, Twilight.”

“They said it would give me dreams about Marine Biology! 'Learn while you sleep' my flank! Not to mention the perverse side effects,” she added with disgust. “I've really been thinking about sex too much lately. Lucky it hasn't managed to work it's way into my subconcious yet.”

Spike thought for a moment. “Well, at least none of those characters has ever tried to sleep with you. That would be a kind of biology.” His eyes went wide. "Oh, I'm sorry! I know I shouldn't be talking about things like that with your, uh, side effects.”

Twilight's eye twitched as she tried to restrain herself, but then her face broke into a mischievous smile as a sudden idea came to her. Could it be...a new type of shipfic? The ponynet must know!

She paused. No, Marines x Navy would be terrible. Nopony would read a shipfic involving real ships.