Summary: Humanity has always thirsted for knowledge. Many times, however, such knowledge has come at a cost. Curiosity killed the cat and, as Lysithea would soon come to learn, many other people as well.

It wasn't rare to find books on Byleth's table. On days where the rain had forced everyone indoors, there was scarce else the man could do to pass the time. The weekend meant there were no classes, lunch had yet to be prepared and places like the cathedral and training grounds were packed with restless students. Without the money or the desire to waste time in the sauna, the only option was to retreat to the privacy of his accommodation, digging into whatever grimoires and encyclopaedias Byleth could take from the library. They were a comfort, reassuring a man educated by blood and battle that he had the academic knowledge to properly teach his students.

The selection Byleth had chosen that day, however, wasn't exactly syllabus material. To even suggest it would probably horrify the vast majority of Garreg Mach residents. There was a reason why those books had been held in a place long forgotten by the surface. A lingering sense of morbid curiosity though kept Byleth glued to the pages. So much so that if it weren't for the gentle voice within his mind, Byleth may very well have ignored the impatient knocking upon his door.

Needless to say, a drenched Lysithea wasn't a particularly happy one.

"Do you mind if I come in, Professor?" it may have been phrased as a question, but there wasn't exactly much of a choice. Having clung as close to the door as possible to spare herself from the rain, Lysithea was stepping through before Byleth had the chance to speak. There was a time and place for pleasantries – neither of them involved rain. "I was hoping you could assist me with some of the questions you've set me. I can't make head nor tails of what you're actually asking of me."

"…Very well. Allow me a few moments to tidy." Byleth responded, punctuated by a sharp flick of his wrist.

One would assume the resulting wind magic would be used to clean up the pile of books sprawled across Byleth's bed and desk. Having already witnessed such a sight, Lysithea didn't react much to the gesture. Unfortunately, that meant the girl was completely defenceless when the violent gust rushed towards her, a childish yelp escaping as she tried to stand strong.

"Wh-what on earth was that?" Lysithea spluttered in disbelief, a shiver passing down her spine as she recovered. When Byleth responded by turning back with a dispassionate gaze, it took all her strength to withhold her indignation.

"You are drier, are you not?" came the stoic response, Lysithea left flapping her lips uselessly as the professor took his seat. When a few experimental taps confirmed that her clothes had lost most of their water, that dumbfounded nature only grew. If it weren't for Byleth's gentle wave towards the bed, she might have remained in that state for who knew how long. As it was, a quick slap to her cheeks brought Lysithea back to reality. "I apologise for the temperature. I've tried to make it more pleasant. it's not as if I can just use fire magic to make it warmer though. Regardless, your question?"

"An Experiment Regarding Warp Technology?" yet Lysithea's attention lay not with the professor, but the worn-out cover sitting beside her. Too absorbed in taking care not to further the damage, the momentary grimace upon Byleth's face went unnoticed as Lysithea began to flip through the pages "Automating teleportation… Extending the range… Everything in here has either been debunked or disproven for several decades."

"Debunked implies failure." Was the simple reply, Byleth plucking the book out of Lysithea's hands with little effort. An attempt would've been made to recover it, if Lysithea wasn't certain that Byleth's dexterity didn't far outclass her own. Even if it were possible, it wasn't her property in the first place. Though Byleth may have been more relaxed when it came to sharing his research and pastimes, needlessly pestering a higher authority for private texts to satiate her curiosity didn't sit well with Lysithea. The only reason Lysithea had done so in the first place was that it was far from the first time. Any other staff member would've had her head for taking one of their texts. "People appear to have assumed verifiability. They didn't realise a falsifier had been found."

"What are you talking about? There have been dozens of attempts to do these kinds of things and they've failed every single time. Don't tell me you're trying to do the same." She scoffed. Just as gravity kept objects glued to the ground and heat produced flame, the laws determining teleportation magic had long been cemented. When hundreds – if not thousands – of magical researchers had failed to find exceptions, there was little reason to continue trying. No matter how many random and insane antics Byleth managed to get into, even he couldn't defy rules set in stone.

"Not me. A man named Charles Fort." Byleth replied, looking down to the book in is hands. "The eighteenth of the Ethereal Moon, imperial year twelve. A device was made to instantaneously transport several people. The destination was said to be unrestricted. Distance would not be an issue. It would absorb ambient magic from the atmosphere. People laughed at it, and then it succeeded."

"Impossible. If a device like that existed, knowledge of it wouldn't be limited to some rotting book. There's no way I'd be able to keep it quiet if I made a breakthrough like that. The profit would be endless, you'd have people scrambling from across the globe for one if it was being sold." Lysithea pondered, leaning forward on the bed. The questions she had intended to ask could wait – a potential game-changer lost to time was far more intriguing. "Besides, if you're not working with two magic circles connected with one another, you wouldn't have the necessary space to engrave a specific location, let alone have a selection available. You just wouldn't be able to fit the symbols inside the circle. Unless this thing was the size of Garreg Mach, an unlimited distance is a pipe dream."

"That implies a single trip." Well… that was obvious. After all, that was what teleportation was, right? Taking something and moving it elsewhere in the span of a second. It wasn't as if you had to send something to a random additional point just to reach the intended destination. Lysithea's confusion must've made its way onto her face, for Byleth gave a small shake of his head before continuing. "When being transported by Warp magic, what do you see?"

"Um… a dark flash or something? I'm guessing that's the magic at work."

"Incorrect. That darkness is not magic. It is nothing." Byleth's statement got the reaction it rightfully deserved – nothing more than a confused noise from his student. "According to Fort, the Warp spell does not directly move the subject from one place to another. The Warp spell contains no components designed to make the subject intangible. This would imply that the subject would be physically moved at high speeds between each point. Not only would this result in visible movement, but the intense speed would also cause injury and whiplash. However, the spell contains the expected transportation elements. Therefore, the Warp spell must transport the subject somewhere. A location that can be moved to and from instantly without injury. A location beyond space and time."

"Beyond space and time?" Lysithea couldn't help but parrot, unaware of how her head tilted in thought. Though there were rumours and legends of spells capable of manipulating time and space, they were that – fabrications and hearsay. If the fact that one of the most common spells could do so became common knowledge, the academic community would be sent into a frenzy. "How can you be sure about something like that? It doesn't exactly sound easy to test."

"That is where the device came into play." The professor continued to explain. If he was bothered by the interruption, it didn't show on his face. Byleth's eyes were too busy gazing towards the faded pages before him, an unreadable distance held within. "Question: What is the purpose of linking two warp circles?"

"To conserve energy. Whereas humans naturally accumulate energy within their bodies, non-sentient substances cannot." It was one of the very first things people were taught when it came to magic. If Lysithea couldn't answer that much, she wouldn't have been able to show her face in class. When you were discussing phenomena that seemed to go against common knowledge however, you could never be too certain. Such was the reason Lysithea's statement held the slightest questioning tone. "Warp circles placed on surfaces require adjustments to their structure to absorb and contain the power necessary for them to function. By having two circles linked, they can share their energy pool while having double the absorption rate."

"Correct. Even then, charging requires time. If this timeless space existed, however, it would not matter. Fort made a device that would accumulate only enough charge to enter this space. Once there, it would charge up the adequate amount to travel to the intended destination. If his theory was correct, it would be able to do so in what appeared to be no time. An additional spell was included to record the time taken." Byleth's comments were followed by the man twisting his hand towards his student, a barely visible image printed upon the page. Scrubbed away by the annuls of history, all that remained was a vaguely cuboid shape. Any chance of replicating the magic used was long erased. "It succeeded. In less than a second, the device appeared far longer than the estimated maximum distance. The time recorded was five minutes. When transporting a rock, six minutes. When transporting a rabbit, eight. He had proved the existence of a dimension beyond time visited during a warp."

"…Professor, I don't like where this is going." Lysithea muttered, her previously lax form rapidly straightening out. She wasn't considered one of the smartest in her year for nothing. "Those results sound too good to be true. This was a discovery that got buried, a man whose name was forgotten by history. If he managed to prove something of this scale, why is the first time I'm hearing of him coming from a book like this? This Fort guy should be lauded by the top researchers."

There were very few occasions where Lysithea got to see Byleth hesitate. With so much skill under his belt and a complete disregard for any type of social norm, little could disturb the mercenary. After having seen Byleth cut down countless bandits with the ease of breathing, witnessing him pause at a story of all things was a novel concept. Regardless, that was what happened, the man's eyes flickering between Lysithea and the book with all the nerves of a child caught doing red-handed. It would take several seconds before the man mustered the strength to respond.

"What happens next is not pleasant. Do you wish to hear?" while the question may have been asked in all seriousness, Lysithea couldn't help the scoff that passed her lips.

"Professor, you've killed several monsters and people in front of us. We've watched things I'm pretty sure some people couldn't dream of." Came the dry response, a wry smile on the girl's face. That she had seen far more horrible things as a child was better left unspoken. "Please, continue. I can handle the mention of a corpse or something."

"…If you are certain." Was that reluctance she was hearing? From Byleth 'Ashen Demon' Eisner? Why, Lysithea never thought she would see the day. "Fort's hubris became his downfall. He did not test one human. He wanted to transport several at once. He did not choose a short distance. He wanted to warp them across the entire continent. Fort had gathered crowds. The device had been charged. People of every kind were gathered to be warped. It was described as a holiday opportunity and a chance to be part of a historic moment. The participants happily agreed. That was when everything went wrong."

For us, it was a matter of seconds. They disappeared with smiles on their faces and returned within a blink of an eye. Little did I realise the millennia of horrors I subjected those poor people to. I underestimated how long they would be trapped in that realm unbound by the laws of reality. When I finally managed to muster the courage to wipe down that blood covered machine and check the spell, what bile remained in my stomach came forth.

For the device to transport so many so far, it had charged for over two thousand years.

There had been only one demented soul unmutilated enough to speak. Even then, their mangled vocal cords had only been able to convey so much. Whether they were male or female, child or adult, even whether they were one or several fused, we could not tell. That they were even alive as that pulsating mass of broken limbs and melted flesh was traumatising enough. None of us cared to ask as they spoke.

The participants had been able to stave themselves at first. I had made sure to warn them of a several minute delay before their arrival, which would translate into seconds. Even when the timer had read days, they had believed either rescue would come or the machine would return them. Stuck in a realm where they were unaffected by hunger, thirst or any other biological function, all they had to do was wait.

As days turned into weeks, however, time consumed their sanity. Trapped in a void with nothing to do, it was only natural for the mentally weak to break. The first attempted to commit suicide, slicing his wrists with a dagger taken in his luggage. To the collective horror of all present though, the man didn't die. No matter how he hacked at his flesh, he continued to live. Even when his hands were hanging by the smallest amount of skin, the man didn't bleed out. Not even tearing his throat had been enough to grant him death.

Faced with such a traumatic sight, many others soon fell into the same state. Tearing themselves apart for any sort of release, only to remain alive. Engaging into wanton lust regardless of age or consent. Brawling over what few provisions people had brought along. It didn't take long before the insane began ravaging other people's bodies, desperately searching for any kind of stimulation in an empty world. Some tried to flee in terror. Others actively welcomed it. Without death, receiving and dealing pain became the only way to pass the days.

It took less than three months for the last of the participants to lose their humanity. After spending so long in an atmosphere drenched in blood and sin, they could no longer be called human. They had long since become brutalised corpses, yet they somehow continued to breathe, to move, to wallow in endless isolation. Though their forms may no longer have resembled what they were before, their broken minds continued with whatever reckless attempts to distract themselves from their own insanity. Some tried to have sex with destroyed genitals, uncaring for who their partner was. Others, having consumed the last remnants of food and drink ages ago, chewed upon decimated flesh.

After those horrific two thousand years however, my machine finally managed to accumulate the charge it required. The unfortunate trapped souls were wrenched from their hellish landscape and brought back into our reality, with all of the natural laws that it came with. The grass was drowned in a wave of blood, every last drop wrung out of their tortured bodies. A woman screamed as a head rolled towards her feet, a dislocated mouth filled with an unspeakable fluid. The sight could be described as nothing more than a mountain of meat and bone, soon drenched in the vomit of those present.

Despite that, it was not the sight that would haunt me the most. No, the honour belongs to what few heads remained connected to bodies, only majorly damaged rather than complete destroyed. Rather than abstract terror or insanity as one might expect… there had been smiles on their faces. In the few moments their brains continued to function when they returned, they had smiled. My experiment not only drove decent men, women and children to turn themselves into… those things, it had even caused death to bring them bliss.

It is with those images burned into my mind that I declare this. My technology must never be used upon a human ever again. Let my work die alongside these unfortunate souls, alongside me when the public inevitably seeks my head for those deaths. Mortals were never intended to mess with forces beyond their comprehension. However tempting the door to another realm may be, attempting to open it will only invite havoc upon our fragile existences.

May the key forever be lost.

Byleth had been prepared, already moving the bucket before Lysithea just as she began to wretch. That there was a witness unaffected enough to accurately recreate the gory scene upon the pages was almost as unbelievable as the event itself. Stoic as he attempted to present himself, even Byleth was not immune to the disgusting sight.

"I-I… apologies, Professor…" Lysithea eventually managed to speak when no more would leave her stomach, accepting the offered glass with trembling hands. "I n-never should've a-asked…"

"However gruesome it may be, history cannot be changed." Came Byleth gentle answer. In any other situation, he may have said more, perhaps given some sort of motivating speech. He had done so with every mercenary who joined after him, all bright-eyed until they witnessed a massacre. "…The rain is heavy. Do you wish to stay the night?"

"If… If that's o-okay with you Professor…"

If anyone had come across them that night, they would've immediately denounced Byleth and Lysithea sharing a bed as scandalous. Met with the tales held within that book and its kin though, it was the only way the two of them could comfortably sleep.