Crashing through the roof is a memorable, if a tad bit painful way to make an entrance. Still, the pony plummeting across the night sky doesn't think about it much. Mostly because they just came to in this world, unaware of their surroundings. Slowly though, they begin to analyse what they can perceive.
A small cart in the middle of the large, open field. Chances of actually hitting it are slim. Density of ground and speed of fall are unknown. Air breathable. Strange sensation. Slight hint of... hunger? Plummeting. Body feels weird. Hard to move. Could also be air pressure. Ground closing in. Estimation about cart is about to be proven untrue.
"Heh, heh, what's that? You say I'm the greatest? Eh heh he..."
The mumbling unicorn is fast asleep, blisfully unaware of the ballistic trouble heading for her. She had a long day, so she decided to rest when night fell. The surroundings seemed nice, if a bit deserted.
And now she is jolted awake by something on the scale of an earthquake. She frantically searches for any sign of hostility, or change. Strangely enough, her usually cozy trailer now has a pony-sized hole in its roof. On the floor, a white figure sits up from the rubble.
Trixie is not a pony to take risks. She only did it twice in her life, and it backfired on her both times.
"Who are you, hooligan?! Be warned, the Great and Powerful Trixie could turn you into dust in a heartbeat!"
The white bat pony emotionlessly stares at her.
"I see. Be assured, I am of no harm to you, Commander Trixie. I merely ended up here by chance... even if it is a very strange chance. I would ever be grateful if you didn't turn me to dust. One time was enough for me."
"Oh well, consider yourself spared," Trixie says nonchalantly. Her brain kicks in a moment later. "Wait, Commander Trixie?"
"My apologies. I only assumed you are the commander of a group because of your immense power. I shall refer to you properly, Queen."
"Um, no, queen is a bit..."
"Then how shall I refer to you, my liege?"
"Well, 'princess' would be nice..." Trixie ponders, "Wait, wait, wait. When did I become your liege?"
"I am sorry, Princess. I have only recently came to this world, so I wanted to serve the strongest. I am quite a capable fighter, I can assure you."
"Well, bat ponies are known for their nimbleness... What is your name?"
The white bat pony bows a little, moonlight reflecting on their black mane.
"My name is Ulquiorra Cifer, Princess, Fourth of the Espada, Death Aspect of Nihilism. I am looking forward to serving you."
Trixie holds up a hoof.
"Hold on for a moment."
The showmare steps to her poorly endowed bookcase, picking a seemingly random book. She opens it, and skims through the pages as fast as an eagle, until something catches her eye.
"Let's see... Educación, El gringo, Emaciado... ah! Espada! 'Sword'... Hm..." She looks at the bat pony absent-mindedly. "So, you recently came to this world, and you were a sword before."
"Not exactly, Princess. 'Espada' was our chosen name, just something to mark the strongest. I was not a sword, but a living... well, spirit being before, for a lack of a better word."
Trixie looks at Ulquiorra with an expression that could be described as dumb if we want to be tactful and honest.
"So you just popped here after—and I'm guessing here—you jumped into some kind of portal that mysteriously appeared from nowhere?" She tries to make a bemused face, but the fact that she has a serious case of bed hair kind of prevents it. Ulquiorra responds with a headshake.
"Actually, I'm inclined to believe that I died."
Trixie is thrown off-track, eyeing the white bat pony suspiciously.
"If you died, then how are you here now?"
The question posed is indeed a valid one; one that Ulquiorra pondered about, too. The bat pony is quick to share the most reliable guess they have.
"I believe either my enormous regenerative capabilities revived me here, or Lord Aizen had rewarded me with a second chance for my services."
"...Well, let me just ask a few questions then." Trixie snorted. The bat pony's expression does not change as they give their answer.
"Of course, Princess. What is it you wish to know?"
"First, what was the extent of your regenerative powers?"
"I was able to regrow any lost limb, or other organs, like eyes, as long as they weren't strictly needed for me to function."
"Uh huh. Then explain this for me: why do you still have a small cut on your face?"
Ulquiorra instinctively reaches up to a spot that suddenly beckons for attention. It is as the showmare says; a small cut is indeed present there. The implications of this are clear: no more regeneration.
"Curious. Then I believe we can safely assume that the second option is true," the bat pony concludes. Trixie, on the other hoof, still looks skeptical.
"Yeah, no. Who exactly is this 'Aizen' guy?"
"He is... was the leader of us arrancar, and us Espada wowed to him. Even though he was a soul reaper, he did not know fear. For hollows, who are born from fears, this could amount him to a god, if we use a comparison fit for more primitive cultures."
Trixie snorts even harder, causing the bat pony to raise an eyebrow.
"I'm sorry, have I said something offending?"
"First of all, you just called us ponies primitive. Second, no leader lets their subordinates die, just to bring them back in an another world. This Aizen sounds like a bad boss to me. Does he mean to use you even after he worked you to death? Or until death, the very least."
Ulquiorra's expression darkens, taking an aggressive pose.
"I'd rather if you didn't mock him, Princess."
Trixie holds her head in her hooves.
"Jeez, stop with the freaking princess already! I was just joking! Also, if your boss is so great, where is everypony else from your group?"
"..." Ulquiorra is at a loss of words. "How did you know that others died, too?"
Trixie shrugs.
"I took a wild guess. Also, you said you were creatures of fear and despair, right? If so, that makes you the bad guys. Princess Celestia would never allow him to do as he pleases here, so guess again. I don't know who this 'Aizen' is, but he can go buck himself for all I care."
Ulquiorra comes to a conclusion. Despite the initial good impressions, this individual is loudmouthed, and condescending towards Aizen-Sama. She needs to be punished. Eyes half-closed, Ulquiorra prepares to hand out righteous punishment... but the familiar feeling never comes. Come to think of it, not even once in this world did Ulquiorra feel the spirit pressure of others. Meanwhile, Trixie looks at the bat pony with interest.
"You're constipated, or something? I think I have some pills somewhere for that," she offers thoughtfully.
"No!" Ulquiorra groans with rising anger. "It was meant to evaporate you in a blast of energy!"
Trixie taps her own sides with exaggerated movements.
"Nope, no evaporation here. Seems like I'm completely unevaporated." She looks at Ulquiorra with a clearly superior expression. "Besides, you are a bat pony. Exhibiting magical prowess as a bat pony is bloody impossible."
"... I see." Ulquiorra nods. Every moment brings a piece of clarity. "So the dominant species here are the ones that can cast 'magic', such as yourself, correct?"
Trixie looks a bit flabberghasted.
"Dominant species? Sure, it's very convenient to use magic to solve our everyday problems, but—"
"Does any other race posess 'magic' other than yours?" Ulquiorra interrupts her. The anxiousness is gone, and the want to learn replaces it.
Trixie hesitates.
"Well... The changelings have a natural affinity to change their appearance... but other than that, not really. I think ponies are the only ones capable of performing advanced magic."
"Then it is simple," Ulquiorra says, "I am a bat pony, and you, as a pony posess capabilities—"
"Whoa, whoa, whoa. We are both ponies, you and I. You're a pegasus, I'm a unicorn, but we're ponies!"
The former Espada pauses, confused.
"I seem to have lost track. I was under the expression that a pony is different from a bat pony. Could you enlighten me about races and their attributes in this world?"
Trixie shrugs.
"It's simple, really. There are three types of ponies: pegasus, unicorn, earth pony, and bat pony. There are four types of ponies: pegasus, unicorn, earth pony, bat pony, and crystal pony. There are FIVE types of ponies: pegasus, unicorn, earth pony, bat pony, crystal pony. And alicorns. Oh, bugger!"
Ulquiorra has a premonition. A premonition that if one wishes to learn about the 'heart', and humans, one might as well start with ponies. Nevertheless, the bat pony takes a neutral stance, eagerly awaiting any tidbit of information.
Meanwhile, Trixie overcame her short mental block, and tries to explain more.
"What I wanted to say was: every type has a sort of inborn ability with them. Pegasi can fly, and manipulate the weather, unicorns can cast spells, and earth ponies can cultivate the soil, and have heightened endurance. Alicorns sorta combine the three, although I've never seen them plow or raise crops. Crystal ponies can emit a kind of love weapon thingy, and bat ponies can... bat? I don't really know about the last two." Trixie stops to think, and starts musing to herself. She does not realise that before Ulquiorra's attentive ears, even mumbling is as clear as a shout in an empty room. "Come to think of it, it might be best if I took you to the Princesses. You just popped into existence, but probably originate from another world, so they must be interested in you." Her eyes lit up. "Maybe I would get some kind of reward from introducing you! Yes, yes, a private stage, ladled with gold, and ornaments of...."
Ulquiorra pays no attention to the delusional showmare, and instead ponders about the correct course of action. The highest authority seems to be the so-called Princess here, so consulting with them would be highly desireable. The bat pony glances at the absorbed showmare. This individual, however has not yet shown true value, despite claiming high arcane versatility. There is one method however, to test her usefulness...
"What is a heart?"
The sudden question throws Trixie off-track, yanking her out of her dream-world.
"You mean like the organ that is responsible for pumping blood through your body?" she asks cautiously. She's met with a headshake, with Ulquiorra being visibly disappointed.
Perhaps it was too much to expect so much from her, the pegasus thinks gloomily, Perhaps it is a question that—
"If you're talking about the metaphorical sense, however," Trixie continues, "it is something that can show compassion; not closing yourself off from others' problems, helping ponies out occassionally, and..." Trixie clearly shows hesitation. "I guess forgiving past misdeeds even though the one who did it was a complete jerk to you and your friends and later returned to enslave your city but was defeated by teamwork and thrown into prison for what she's done but you rather choose to give her another chance at redemption just because you believe her guilt about what happened is real which is true but you have absolutely no way of knowing it just have faith in her—HAAAAAH!" Trixie starts panting, a little out of breath from her rambling. She offers Ulquiorra a weak smile. "That didn't make much sense to you, did it?"
A long silence looms before the bat pony answers.
"No, it did not make sense to me. I intend to rectify that, though."
Trixie furrows her brow.
"I am not letting you touch my butt!"
The two stare at each other for a minute before Ulquiorra speaks.
"I meant it in the 'remedy the situation' sense."
The showmare's relief is both visible and audible.
"Thank Luna, I thought it was about your special talent."
"Special talent?" Ulquiorra asks confused.
"Yeah, you know the one that your cutie mark—oh, right, you don't know. Listen, the only thing the five – SIX – pony races have in common apart from their general appearance is the cutie mark. It represents a pony's special talent, that they have exceptional affinity for. For instance," she says, pointing to her own, "my cutie mark signifies I am good with stage entertainment, and magic. I didn't recognise yours before, because it was so dark that I thought that it was just a pattern in your fur."
She points to Ulquiorra's flank, and true to her words, a black patch of fur is indeed there. Upon closer inspection, it looks like an ellipsis with another inside. Ulquiorra can't place it for a minute, but then the connection becomes clear. The cutie mark is very reminiscent of a hollow's hole in their chest. What would it's meaning be, though?
"Hey, if your talent is holes, can you take a look at where you crashed through my roof?"
Ulquiorra shrugs, unconsciously flapping up to the hole.
"What exactly do you expect me to do? Just touch it and make it all go aw—"
While speaking, the bat pony motions towards the hole, accidentally colliding with it's edge. To both ponies' surprise, the hole moves a little. Being a very pragmatical person, Ulquiorra tries again, and this time the hole moves all the way to a corner, then slips on a wall when the bat pony applies more pressure.
"... This is completely ridiculous."
Trixie glances at the ceiling where the hole was. It is just like it was yesterday, not even the smallest sign to point to that it was in many pieces a second ago. She also notices that the rubble has disappeared from the floor. She shrugs. Then an idea strikes her.
"Say, can you shrink it?"
Ulquiorra positions the hole between the still unfamiliar hooves, and tries to push the edges toward each other. To no small surprise of either of them, it works. The pegasus doesn't stop until the hole is less than an inch long.
"So that wasn't magic?" Ulquiorra asks, unconsciously discovering sarcasm. Trixie shrugs again.
"Hey, I don't make the rules, I just blindly obey them. Bes—aaaagh!" Her words are strifled with a large yawn. "Look, can we continue this conversation in the morning? I'm tired, you only came to existence recently, so what do you say we go into that niiiice looking bed and sleep until ten?"
A past conversation between fellow arrancars flashes in Ulquiorra's mind.
"Wouldn't sleeping in the same bed be...immoral?"
Trixie looks genuinely surprised.
"Why? Just two mares sleeping together after an eventful night! Wait, that didn't sound right..."
Ulquiorra experiences a new emotion again. Panic.
"Two WHAT?!" Even though it sounds ridiculous, the sentiment wasn't just a biologically inexperienced guess, but the truth. Ulquiorra sees the problem now: when crashing through the roof, she deliberately ignored her body's warnings, because of the pain she felt. Now that the pain has gone away, something else has also gone away. Not that she had any problem with being female, but it still upset her. Must be hormones, with the new living body and whatnot. Regardless, she knows what the proper action is there to take. Might as well proceed with it.
"WHAT THE FLYING—?!"