Welcome back folks! This time, I kind of wanted to mess about with the dynamic that I have going here. Originally my idea was simply 'ooh, let's blow something up' but it kind of evolved into what it is now; something a little more bittersweet than I intended by the end. Either way, I hope that you enjoy it just as much as the previous ones!

Summary: In his free time, Byleth finds himself exploring new potential weapons and techniques too dangerous to involve the students with. It's only natural then that one of the most inquisitive would find herself embroiled in the situation. Well, perhaps it's better to say forced her way into it...


The light taps of chalk against a blackboard filled the room, a calming ambient noise that Byleth was slowly growing to like. It would never match the soothing sounds of a crackling fire, nor did it occupy the mind like some of the tunes the students were singing did, but it allayed the silence of solitude well enough.

Byleth paused momentarily to gaze over his musings, faced with an admittedly poor diagram surrounded by so many thoughts as to be partially illegible. That was simply what happened when you just wrote down everything that came to mind, he supposed. He could refine the details later when he was certain that his mental tirade was going anywhere useful.

A low hum escaped the professor as he reached to his side, the rubber wiping away the nonsensical to be replaced by the practical. Even if what Byleth was attempting wasn't exactly normal, he was a mere mortal; there were limits to what human hands could hope to create.

"Professor? What are you still doing here?" a voice spoke from behind, Byleth turning to see the youngest student with a candle in hand. Had it gotten so late already? "You weren't present for the evening meal. Seeing as you're always there eating with everyone, I thought I should check on you."

"Lysithea. Do not worry. I was merely lost in thoughts." Byleth replied softly, placing down his utensils and dusting himself off. Nothing helped the mind collect itself more than a distraction.

"All alone?" Lysithea replied, a small pinch extinguishing the tiny flame in her hands as she entered the classroom, the light of the torches surrounding more than adequate compared to the tiny candle she had hastily prepared. "What are you working on that needs so much attention? No offence Professor, but even as a teacher, I never took you for the solitary academic type."

"No, you are correct." Byleth was quick to reply.

Compared to the rambunctious noise of students chatting and eating he had become accustomed to during his stay at Garreg Mach, the classroom was almost stifling in its silence. If it weren't for the fact that it would be remiss of him to leave the Monastery, Byleth would've no doubt decided to seat himself in an open field with a campfire, surrounded by good friends that he could bounce his ideas off. With no fires to be held in the gardens and everyone busy when he began his work, Byleth had simply settled for working alone in the classroom instead.

"I am creating an explosive."

"E-excuse me?"

"I have been researching methods to enhance our effectiveness in combat. Methods to counter weaknesses." Byleth explained, an arm gesturing loosely to the blackboard and the ridiculous amount of writing upon it. "Plan number twenty-four is utilising explosives."

"But… we already use explosives." Lysithea rightfully pointed out, tilting her head with visible confusion.

Being one of the main magic practitioners of the Golden Deer, Lysithea was the one who had used them the most in fact. Whenever the situation had called for it, it had always been her flames that had ignited the fuses, the barrels quickly pushed towards whatever insurmountable enemy was in their way so they could eviscerate all in a large radius.

"Indeed. However, I want to expand their utility. As they are, they require men to move the carts. Their weight restricts their movement. They produce a large target for enemy magic users. They are only good for monsters and demolition." Byleth countered with a shake of his head, Lysithea bringing her fingers to her chin in thought.

"Well, I suppose that isn't incorrect… but I don't see why we would use it for anything else." The white-haired girl muttered. "If enemies are targeting it, then we already have people protecting the payload and monsters don't tend to target the explosives even when they're in close range."

"That is true. However, I want to make an explosive viable for archery." Byleth said, stepping over to the board. "An explosive that can be used by anyone. Easily mounted on an arrow. Detonated with contact or a timer. It would bolster the strength of the archers with fewer drawbacks."

It was an… interesting idea in Lysithea's eyes. If a non-magic user wished to ignite explosive barrels, they would need to have some sort of fire source and they were woefully hard to bring into a battlefield. If explosives could be activated by other inclusive means, then they would be far easier to utilise on a greater scale.

"I see, then it would allow archers to deal with more heavily armoured units or ruin shields." Lysithea said, a momentarily gleam entering her eyes. "A timer would be better; contact detonation would be quicker to deploy, but you risk someone blowing themselves up with a particularly harsh bump."

Byleth didn't answer, merely reaching for his rubber and scrubbing off 'contact' from the blackboard. It didn't really make much of a difference to the rambling mess, but it was a start to refining his thoughts.

"Actually, now that I think about it… I remember reading something that might help you with this. I can get it for you now!" Lysithea began, only for both her steps and face to falter before she even got to the door. "…Except the library's closed because it's already so late. How irritating. Well, I can probably still look over your ideas and see what's reasonable or not. Everything's easier with two heads after all-"

"You have shown me it is late. There is no point proceeding. I shall retire for the night. See that you do as well." Byleth stated, stretching slightly as he went to extinguish the torches surrounding.

"But wait Professor! Surely you can't just stop now, not when there's the potential to make good progress!" Lysithea quickly protested, but the professor did not halt in his job, the classroom slowly growing as dark as the sky outside. "What if you go to sleep and forget what we just talked about?"

Her argument was enough to make Byleth pause before the final torch could be extinguished, a smug smile appearing on her face as he went back to the blackboard to pick up the chalk.

That smug smile was naturally destroyed when all Byleth did was write 'ask Lysithea' before summarily walking away, leaving the white haired girl blinkingly owlishly in the darkness.

"It is better to rest and recover than to carry on and potentially make mistakes. That could get you killed on the battlefield. Good night Lysithea."

"Hmph, how rude." Lysithea muttered with folded arms before a curious smile appeared on her face. After all, while Byleth might not have the precision to light a delicate fire that wasn't meant to burn a man alive, she did. The lit candle now sitting before the blackboard was prove of that. "But, it won't hurt anyone if I have a little look at his work, right? I've always wanted to see what a professor's research is like. If I'm lucky, I might help him make a breakthrough…"


Byleth returned early the next morning, the sun still rising from its sleeping place as he made his way to the classroom. It wasn't a necessity, all Sundays being days off from work, but Byleth's dangerous lifestyle of the past would have him wake no later.

Thank goodness he had though, for it meant he was the only one to witness a blackboard far fuller than before, a completely melted candle and Lysithea blissfully dosing away with the desks as a makeshift bed. From the chalk that stained her hands and now her clothes from where she had moved through her slumber, it was clear what had occurred.

Byleth gave a near silent sigh as he moved to the blackboard. Though Lysithea never was one to act out against the authorities, she was spirited and curious to a fault. With how engaged she had appeared before, it was only natural that leaving her would make her act in such a way.

He couldn't deny that her work was something to look at however. Even as tired as she must've been, Lysithea had left note after note next to his own scribbles, additions to improve his designs or reasons as to why such things would fail to work in her respectful, yet somewhat sharp tone. The amount of progress she had made was to be respected.

Which was why Byleth, in order to wake his student, decided to send a sharp blast of wind in her direction.

With an inelegant yelp, Lysithea found herself rolling off the desk, landing face first onto the unforgiving stone. Fortunately, though the landing wasn't what you would call painless, both professor and student were somewhat learned in the art of healing magic, meaning that Byleth was able to ease whatever injuries might've appeared.

"What the-!?" Lysithea sluggishly began, only to realise her the harsh classroom was not her bedroom and the teacher watching patiently was not some sort of perverted intruder. "Oh, Professor… it seems as if I've stayed here longer than I expected."

"I thought I told you to sleep." Byleth stated with folded arms, Lysithea unwilling to meet his eyes as an innocent whistle came from her lips.

"Well, I technically did sleep Professor." Lysithea weakly reasoned before her face fell slightly. "I'm sorry. Some of the things you were suggesting just seemed so strange and yet functional with just a little bit of tweaking, I just couldn't help myself. I mean, I don't even recognise a whole portion of the concepts you were talking about!"

She wilted further under the professor's look, Byleth giving a tiny sigh. The reasons behind her decision were somewhat acceptable; he had stolen ideas from all his travels and some of them were better classed as esoteric, perfect for the curious intellectual. He could easily imagine Annette doing the same thing had he overseen the Blue Lions.

"I have no choice. You will have to be punished. You disobeyed my orders." Byleth muttered, his eyes narrowing in Lysithea's direction. "On the battlefield, you could die. Orders are given for a reason – whether it be your health or your survival."

"Of course, Professor. I understand."

"As punishment, you will be assisting me with my research. If you had any plans for today, cancel them. If you had plans with someone, apologise and send them to me." Byleth quickly continued, peering at the blackboard with a short nod. "I will expect you at the entrance gate. Clean up and meet me there."

And in the span of a second, Lysithea perked up incredibly, rising to her feet with a miraculous level of energy.

"R-right!"

Seeing her enthusiasm as Lysithea rushed off to prepare herself for the day, Byleth let the smallest of smiles appear on his face before it was immediately wiped off, just in time for the newest arrival to enter.

"Come on, really? You're going to pretend that was anything close to a punishment?" Jeralt asked with a smirk as he leant against the doorway. Byleth merely shrugged in response.

"I don't do detention."


Those in the market wouldn't question the sudden mass purchasing that Byleth underwent; it wasn't odd for professors of the Officer's Academy to suddenly require large volumes of equipment and considering how little he had purchased before, it was about time for Byleth to restock. The fact that he had Lysithea eagerly following behind him was practically ignored as well, especially when it was explained to be a part of her 'punishment'.

Well, people did question what on earth someone like Lysithea could do to earn a punishment, but they quickly had a chuckle at the censored story to the white haired girl's embarrassment.

What it meant was that both professor and student were left with an incredible amount of materials and nobody realising their true intentions. As they were, it was hard for the common man to understand how they could be put together in any meaningful man.

Then again, neither Lysithea nor Byleth could be considered common. One had learned more than any girl of her age had any right knowing about explosives after her extensive impromptu research session. The other had been taught how to fashion items out of makeshift parts for years to desperate situations both financial and fatal. Together, they were a potent combination.

One would be forgiven for believing their roles were reversed; with their equipment in hand, they naturally fell into a rather comfortable routine with Lysithea reading off their notes and Byleth giving them material form. Sure, it may have resulted in the professor receiving more than a fair few explosions to the face, but they were loath to imagine how much worse it would be with someone less skilled with their hands.

By the time they eventually paused, the sun had passed far across the sky and they had undoubtedly missed a meal. They were fortunate enough that Byleth had the initiative to purchase some snacks, apples in hand as they gazed upon their handiwork.

"It… certainly doesn't look like much." Was all Lysithea had to say as she looked on, struggling to hold herself back from picking it up for closer analysis.

After all, one of their creations looked no different from your typical arrow, save for perhaps the feintest of patterns decorating the arrowhead. Then again, under normal circumstances, it quite literally was just a normal arrow and it would feel and fly as such.

"We have yet to test this version. It may not work." Byleth muttered, carefully taking the shaft of the arrow between his fingers and reaching for the burn marred bow that sat at his side. Though it had faced much in the way of tribulations, it still had one more shot left in it at least.

Drawing back the battered bow's string, Byleth let his finger gently glide onto the small circle upon the side of the arrow's wood, the smallest iota of magical energy pouring through his fingertip into the projectile while he aimed. It was such that even the weakest person magically would be able to mimic the action.

The result was the smallest veins of rich pearlescent light that began to crawl towards the arrowhead, several intricately designed runes decorating the metal soon aglow with power as Byleth steadied his shot.

It wouldn't give him long. They had messed about with the timing to make sure there was enough time to aim before the arrow exploded but had originally came up short every time.

While it was far easier to handle timing with the bomb-tipped arrow, the altered arrowhead meant that the flight path was too messed up to be easily integrated into the current archers' quivers. If the timing worked, then their current option would be far superior in all aspects.

The arrow flew and the world changed.

The problem was that they had needed a way to form a sufficiently large enough explosion from the smallest amount of magical energy possible. Their current solution had come late in Lysithea's all-nighter when she chanced upon a book that told of ambient energy within the air and how certain runic arrays could be modified in order to absorb said power into vessels or rituals. It had been a godsend.

The book failed to explain just how sensitive the absorption rune was however, meaning that when Lysithea had Byleth etch it into their prototype, neither were aware of just how much energy it had absorbed from the air as it flew towards the target.

A fierce roar shook the earth as a wave of blinding flame flew towards them. Lysithea was fortunate enough that Byleth was able to shield her before the full force of the explosion rocked her world, burning heat blasting against her skin as they collapsed to the ground. Compared to the noise the explosion caused, her cry of alarm was easily drowned out.


Once her sight returned, Lysithea let out a small groan, rubbing her eyes as she wormed out of Byleth's hold. The act required a little bit of force; though the danger had disappeared, it seemed that the blue haired man was reluctant to release her.

Except when Lysithea did break out, it was made clear that it was through no conscious effort on Byleth's part; staring at the scorched skin exposed to the open air on Byleth's back and the singed hair that marred his head, there was no doubt the pain had caused the Professor to pass out.

"Professor…?" the imperial voice that spoke behind her caused Lysithea to immediately freeze; there were none who would fail to recognise that tone even in its anger. "Lysithea Von Ordelia… just what is going on here!?"

"Archbishop Rhea…!"

Lysithea found herself momentarily lost for words. In the recesses of her mind, she was all too aware that neither of them had done anything wrong, but to try and claim such a thing while cradling her professor's horribly burnt body after a massive explosion that had absolutely decimated their target and much of the earth behind it would spell her death.

Instead, she felt whatever response die in the back of her throat, Lysithea merely letting her mouth flap uselessly until she felt both Claude and Hilda help her to her feet so Marianne and all the other quickly gathered healers could attend to Byleth.

"W-we were e-experimenting…" the girl eventually managed to pitifully spit out, only the smallest of gestures from her house's leader showing that she had been heard. After all, most were too busy returning to wherever they had been drawn from, gathered as a hasty defence to a non-existent threat.

Though the truth of an experiment gone seriously wrong would slowly make its way around Garreg Mach, the rampant and far juicier rumours that were bound to form gained traction far quicker. While many were already slightly fearful of Lysithea's capacity for destructive magic, news of what occurred only made such fear worse and open.

Needless to say, the project was never returned to.


And for this little tale, we have reached our end. I suppose this is a story where reality ensues a little bit; if you're going to test explosives, even magical ones, it's going to be a dangerous business. I feared that this would just be a bunch of predictable and one-note fluff stories, so I ended up shaking things up a bit. It may not have been the best way, but I hope this proves I want to document all of their relationship, not just the cute moments.

Super hero time! See you next time!