Work Text:
Gen’s romantic relationship with Senku was relatively new, and they hadn’t yet put a title on what they were exactly. He wasn’t particularly bothered, more focused on the fact that he had somehow managed to get Senku “emotions are a waste of resources” Ishigami to fall for him without even trying and that he didn’t have to hold back from kissing him whenever he wanted to anymore.
Being in a relationship with Senku was unlike any of Gen’s previous relationships, and he had gone in knowing not to expect flowers or candlelit dinners or other romantic gestures, which was actually sort of nice when he thought about it. He didn’t have to worry about pretending to be something he wasn’t, put on a charming mask, play the role of the dutiful doting boyfriend or give exaggerated reactions in fear of disappointing his partner.
Many people assumed Gen was the type to want to be spoiled by their partner, and while it was true that he was very much a lover of the finer things in life, he was also a rather independent man capable of getting those things himself. He’d always struggled with being taken care of, having learned at a young age that big gestures were often hiding ulterior motives and hidden strings.
His previous partners hadn’t dissuaded him of the notion. They would shower him with fancy gifts - expensive dinners, pricey clothes and accessories, grand gestures that were more about them showing off than showing that they cared for him - usually with the unspoken but heavily implied expectation of reciprocation in the use of his industry connections or through sexual favors. It was exhausting having to smile and pretend to be excited as he waited for the other shoe to drop.
But with Senku, he didn’t have to worry about that. There were no games, no strings, no expectations beyond what either was willing to give.
Senku was honest. Honest about what he was willing and able to do in the parameters of a romantic relationship, and more importantly what he wasn’t.
Gen knew not to expect flashy romantic gestures or gifts just because, and he didn’t mind one bit.
The two had come together with clear expectations, and they worked because of it.
Then he found a rock on his bedroll.
Not the oddest thing, he’d found rocks and dirt in unexpected places before. It came with the territory of wandering through the woods and sharing space with a walking science lab over a storage room- sometimes things just sort of showed up in odd places.
But this wasn’t any ordinary rock. It was a cluster of little pale pink crystals, somewhat translucent, about the size of a ping pong ball. Rose quartz, his mind helpfully supplied, not particularly useful for much outside of aesthetics or possibly to be ground up for ceramics or some other crafting project if he recalled one of Senku’s many science lectures correctly.
It was rather pretty, though, and he found himself tucking it into one of the hidden pockets of his kimono for safe keeping.
Then a few days later another one showed up, on the tray he used to transport snacks and tea to the lab when Senku had gone too long without a break.
This one was a dark red, nearly black, with little veins running through it of yellow and orange. It was gorgeous, even unpolished and rough, probably garnet or something similar, but Gen had no idea where it had come from.
He suspected Suika, the child fond of pretty things and always lurking about, or maybe Chrome dropping things in his excitement as he hurried from one task to another.
In any case, he pocketed it, taking the tea kettle and continuing with his plan to force Senku to stop for lunch.
The third stone a week or so later was larger than the others, a lump of craggly gray rock that fit in the palm of his hand with a hollow indent full of shimmering white and purple. That one had been set on his folded kimono, placed so precisely there was no possible way it had been dropped or otherwise misplaced.
Once was an accident, twice was coincidence, and they had quickly arrived at a pattern.
So Gen what he did best and he watched.
He paid close attention when Chrome talked about the many materials he had gathered, showing off bits and bobs amassed over the years or found on recent trips, waiting to see if one of them would mysteriously reappear in his belongings.
He kept note of all the things Suika brought to him and others, usually pretty flowers or interesting oddities like cicada shells, all with the pride and open curiosity one would expect from a child her age.
He even watched Ginro, making sure the guard hadn’t involved him in whatever his most recent silly prank was - though it seemed his current targets were Jasper and Turquoise and whatever he was doing didn’t involve any sort of rocks or stones.
The most recent stone showed up after another one of Senku’s all-nighters. Gen had wheedled and cajoled the scientist, making sure to bring him food and forcing him to drink water, and finally had been able to drag the drowsy man back to the observatory for some much needed sleep late the following afternoon.
In the morning, there was a smooth piece of mottled green rock resting next to Gen’s pillow.
“Is there some sort of reverse rock based tooth fairy in the hundred tales or something?” he muttered, turning the stone over in his palm a few times, noting the small bands of beige running through the surface.
Suddenly his movements paused and he glanced over towards Senku’s bedroll, already tidied up from when the scientist managed to sneak away before Gen woke up, surely already back in his lab and hard at work.
The idea was silly, honestly, and his first instinct was to disregard the notion entirely.
But the more he thought about it, the more likely it seemed.
Because of course Senku wouldn’t give him flowers or candy or anything like that as a romantic gesture.
For some reason, Senku would give him rocks.
—
He waited to mention it until that evening when he was bringing Senku dinner.
“The angest-stray thing has been happening recently,” he began, taking the empty seat next to him and one of the bread rolls off the tray.
Senku hummed in acknowledgement but didn’t look away from what he was doing - some intensely detailed schematic for what he was sure would be an impressive piece of machinery - brow knit in focus and the tip of his tongue poking out in the way that always made Gen want to kiss him.
“I keep finding rocks in my things.”
Senku’s hand paused for the briefest of moments, almost unnoticeable if not for how closely Gen was watching him.
“That’s what happens when you spend all day in the woods dodging work, Mentalist.”
Gen clicked his tongue, setting the piece of jade on the table between them, “If I’m able to pick up polished jade just by taking a walk, I eriously-say picked the wrong career.”
Senku glanced at the rock, then at Gen, then immediately back to what he was doing in an obvious attempt to look busy.
Gen humored him for another moment or two, finishing off his bread roll and taking a sip of tea.
“So is there a particular reason for why I uddenly-say have a growing collection of semi-precious stones?”
Senku’s ears went red, the flush creeping up the back of his neck as his shoulders hunched up. Gen had to bite back a grin - it was always cute when he managed to fluster him.
“It’s nothing,” he muttered, “just… interesting geology. You like shiny things.”
“Hmm, I do like shiny things,” Gen acknowledged, “as do many others, yet I’m the only one finding fancy rocks lying about as far as I can tell.”
Senku frowned, staring down at his project for a long moment before finally giving a long-suffering sigh, as if Gen had asked him to recite Shakespeare.
“It’s… a penguin thing,” he finally mumbled, words low and quiet as if it pained him to admit.
Gen blinked. “…penguin thing?”
“Adelie penguins,” Senku grumbled, grabbing his bowl of stew off the tray and aggressively stirring it. “Males collect nice rocks for potential mates to build nests. It’s an evolutionary behavior, signifying their ability to provide.”
Gen stared.
“So…you’re giving me rocks because you’re… nesting?”
“No! I mean-” Senku scowled, “sort of. Shut up, don’t make it a thing.”
Gen found himself smiling, “It seems like a thing. A very cute, somewhat embarrassing thing.”
Senku grunted, pointedly taking a heaping bite of his stew so he wouldn’t have to reply.
“It’s sweet, really. You’re giving me rocks because you’re a penguin in love.”
Senku choked, pounding on his chest to try and clear his airways as he stared at Gen in shock. “I am not,” he coughed again, voice a raspy wheeze. “I never said love.”
“Hmm, suppose you didn’t. You said potential mates… should I be concerned that this is all a ploy to get into my pants?“ he gasped theatrically, “Senku-chan, you cad! And here I thought we had something special.”
Senku groaned, half in frustration, half in embarrassment as he drank his tea, pointedly avoiding looking at Gen as he muttered to himself.
“What was that, my little penguin?”
“I didn’t know what else to do,” Senku huffed, cheeks red and expression pinched. “Not like I can take you on a date or anything and even if giving flowers wasn’t stupid, you have enough of them… I’m not about to start acting like Taiju or Ryusui so I figured out something else I could do. Cause now we’re… y’know?”
“Penguin mates?” Gen preened, heart giving a traitorous little flutter, because despite all the bluster and teasing this was why it worked. Senku’s affection was strange, quiet, unpolished - but it was honest.
Senku scrubbed a hand down his face, mumbling something that sounded suspiciously like why did I think this was a good idea?
“I think it’s sweet. And very you. You’re right about the flowers and I’m not really sure what I would do if you started acting differently, considering you being a total dork is one of the things I love about you.”
There was a long pause before Senku glanced up at him shyly, voice quiet, “...yeah?”
Gen felt his heart melt - but not enough to keep him from teasing some more.
He held up his left hand, wiggling his fingers, “So when can I expect to see a diamond?”
Senku’s eyes widened, flushing straight to his hairline as his mouth worked uselessly for a few moments. “Huh?”
Gen burst into laughter, the sound bubbling up bright and unrestrained at Senku’s panicked expression.
“We’ve barely been dating three months!”
“You and Ruri weren’t even dating when you married her,” Gen replied with a dramatic pout, somewhat ruined by how he couldn’t stop giggling.
Senku groaned, dropping his head to the table with a loud thunk, “You are never going to let me live that down, are you?”
“Oh absolutely not,” Gen beamed, getting to his feet and nudging the bowl of stew closer to the grumbling scientist. “Now eat your dinner, I’d like to see my mate come to bed at a reasonable time tonight.”
Senku swatted at him blindly and Gen laughed.
Leaning down, he pressed a soft kiss to the crown of Senku’s head, “Thank you for the rocks, Penguin-chan.”
Senku huffed, turning his head just enough to give him what Gen assumed he thought was a withering look but was more of an endearingly embarrassed pout. “Don’t get used to it.”
“Of course not,” Gen grinned, “I’ll cherish every pebble as if it were the last I’ll ever receive.”
Senku snorted, eyes softening in a way that Gen still wasn’t used to - warm and affectionate and sweet, the way that made Gen’s heart skip a beat and made all the teasing worthwhile.
Gen pressed another kiss to his temple and muttered something about having plans with Ukyo, snatching the piece of jade off the table and scurrying away before Senku could see how he was blushing.
The next morning Gen found a beautifully marbled piece of agate sitting next to his pillow.
He didn’t say anything about it when he saw Senku in the lab, didn’t tease or prod or make some ridiculous joke about a penguin wedding.
But he did tuck it carefully into the pouch where he kept all the others - his growing collection of sweet gestures, tokens of an affection Senku hadn’t had the words for.
Just in case they ever needed to build a nest.