AN: This is pretty self-indulgent as I haven't found JJK/KHR crossover that would satisfy my craving. Also, I'm fairly new to JJK fandom, so apologies in advance if I get anything wrong. And timeline-wise this set post-Reborn and Star Plasma arc, Geto already left. Oh, and Tsuna is a girl here. Other than that, I hope you'll like the fic.
There are a few things you should know about Gojo Satoru: he's the strongest, a god born of humans whose birth forever changed the balance of the world; everything came naturally to him. What he is not good at, however, — and he admits this in his heart of hearts — is taking care of kids. Although servants back at Gojo Clan Estate catered to his every want and whim, they were distant. The same went for his parents; he never knew a loving word or touch from them. To them, he was simply an heir, something they could show and say: "He's a Gojo and the strongest jujutsu sorcerer alive." Sugu—his best friend, his other half was the one who gave love and care freely and easily, compared to him, the personification of winter and infinity. And maybe that's why Suguru fell apart, and left them, with Satoru noticing too late. Jujutsu World is cruel and has no place for love.
This lack of understanding of how to give love and care is exactly the reason why he freaks out internally when meeting the kids he orphaned. Logically, Satoru knows he has no obligations or responsibility towards them whatsoever — after all their father ruined everything he held dear, — but children shouldn't be held accountable for their parents' sins. He also knows he can simply throw the money he has in spades at them, let someone else be the caretaker, and be done with it, but after hearing Megumi speak matter-of-factly about how he and his sister were abandoned by their parents and calmly accepting it, something in Satoru twists. No, he won't let them grow up in a house too big, with only a caretaker and servants for the company, this isn't what they need. He's not Suguru, but he can do this, right? He's Gojo Satoru, after all.
The usually prideful words sound hollow to his ears now, meaningless, but he brushes them off to focus on his new objective. This is why he leaves the Fushiguro siblings after the promise to take care of Zenin scumbags because the first order of business is to consult the expert on raising kids 101. Shoko is out since, as far as he knows, she doesn't have younger siblings, and he isn't sure she would help him. After Suguru left, she distanced herself, focusing on med school. Toji turned their promises and friendship and hopes to ashes with Satoru still clinging to them desperately. Anything to chase away the loneliness, the void left by his friends.
But his pain and issues aside, there is a person he could ask for advice. And she wouldn't turn him away.
Hopefully.
Gojo Satoru meets Sawada Setsuna on a hot day, months before the fateful Star Plasma Vessel mission. He is happily eating sweets, having escaped Yaga's nagging when something small bumps into him. Looking down he sees that it's a kid, about nine years, maybe younger. On the ground between the two of them lies the kid's ice cream. Grape, it looks like. The kid — who has a weird afro and cow costume, blegh, what a horrid taste — raises his green watery eyes at Satoru.
"Stupid old man!" the kid exclaims angrily. His lower lip wobbles as the kid struggles not to cry. "You made Lambo-sama drop his ice cream!"
"Huh?!" Satoru is very proud of his handsome appearance, so some brat calling him old simply because of his snow-white hair causes him to take great offense. Suguru would call him an idiot for arguing with a kid, but whatever. His gorgeous hair is on the line here! And what Suguru doesn't know won't hurt him. "Who do you think you're calling old, you snot-nosed brat? You are the one who bumped into me!"
"And you are the one with glasses and white hair, so totally old man!" the kid retorts. "And you're freakishly tall compared to me, so of course you wouldn't notice me, so you're at fault!"
That's it, the brat is done now. Annoyed beyond belief, Satoru is about to teach the runt a lesson when a melodic voice calls out, startling them both.
"Lambo!"
Tears and distress are instantly forgotten as Lambo— Geez, what kind of name is that?—brightens, calling back. "Tsuna-nee!"
Satoru turns to look in that direction, curious.
A girl around Satoru's age is heading towards them. She's rather lovely with long chocolate hair and eyes, tall for a girl too — 5 '11 if Satoru's estimate is correct, which of course it is correct,— and he prepares to turn on his charm… only for his Six Eyes to receive the full blast of strange orange fire, surrounding her like a cocoon. Now that he looks for it, the brat has the same bubble around him, only green and electric like lightning, reaching towards the girl.
What the hell? It is not the Cursed Energy. He has it, surrounded by it every day, knows the feel of it, and what those two have is the complete opposite, even if the runt is upset right now and could produce the wisps of Cursed Energy in theory, not amplifying whatever abilities he has. This… fire whatever it is, is not bad, just confusing. And interesting, he has to admit. Finally something new and exciting!
Not to mention, the girl's fire is inviting and warm. He feels like a moth drawn to flame and he wouldn't mind burning in it…
"Lambo!" the girl's scolding tone snaps Satoru back to reality. She looks at her brother reproachingly, hands on her hips. Their bubbles touch, not quite mixing like a rainbow. "I told you not to run ahead, you could have gotten lost!"
"I'm sorry, Tsuna-nee!" the brat whines clearly not sorry at all. "But that snow-haired baka made me drop my ice cream!"
"Snow-haired baka?" the girl parrots confusingly and notices Satoru at last. "Oh."
He streches his lips in a flirty grin, knowing it was his time to shine. "Gojo Satoru. May I know the name of this lovely nee-san?"
Satoru expects some kind of recognition of his name or swooning over his dashing looks in response, but all he gets is a name.
"Sawada Setsuna," she says in return with a smile. The lack of reaction is vaguely disappointing. "I'm sorry about Lambo, he can be a handful."
"I've noticed," his smile became somewhat strained as his eyebrow twitched in annoyance at the reminder. Not to mention, he felt like Setsuna's eyes stared into his very soul. Did she have a technique similar to Six Eyes, or something?"But at least I met his beautiful older sister."
The compliment falls on deaf ears as she says, "C'mon, Lambo, Fuuta, and I-Pin are waiting for us."
"But my ice cream…!"
"I'll buy you another one," the girl promises the brat. "Now, apologize to Gojo-san, and let's go."
"Sorry for bumping into you," the runt mumbles, the apology blatantly insincere. Well, two could play this game.
"No hard feelings, kiddo," he accepts with the fake cheer. "Just watch where are you going next time."
"We'll be on our way then," Setsuna says, relieved. "Have a nice day, Gojo-san."
"You too, hope we see each other again," He lowers his glasses so Setsuna can see his wink. Maybe this will get her to react somehow.
Alas, another disappointment awaited him as Setsuna merely smiled, not promising anything. Considering the matter resolved, she turned around to leave, and the brat seeing his sister distracted, decided to get the last word in by sticking his tongue out at him.
That little…! Not to be outdone by some kid, Satoru copies the gesture. The brat's expression is priceless before he and his sister are swallowed by the crowd, their colorful bubbles gone with them.
Huh, what an interesting outing it turned out to be. He should cut classes more often. Mind still occupied by the meeting and strange fire, he returns to Jujutsu Tech to exasperated Shoko and Suguru, and furious Yaga. He doesn't tell them about the strange siblings or their fire. Something inside him wants to keep that only to himself.
Maybe he selfishly didn't want to share the phantom warmth of Setsuna's fire.
Everybody knows he's spoiled, after all.
They meet a few times after that first time. Namimori is a boring town, while the Sawada family and their associates are anything but. He's introduced to Nana, who's just as warm and inviting as her daughter, despite not having a lick of Cursed Energy or that fire, and who accepts him without questions, a polar opposite of his own mother; he's introduced to Tsuna's tutor, who's clearly a dangerous killer, but is caring towards her and other members of the household; he's introduced to Fuuta, who's good with numbers, Bianchi, whose food shouldn't be touched, let alone eaten, and I-Pin, who gifts him a picture of himself and others, a big "Welcome to the family!" made with crayons at the end of his first visit.
He never felt so much warmth as he did then. He was so overwhelmed that he almost cried. Thank fuck, he had glasses on to hide this shame.
Tsuna's parents and siblings are not the only ones Satoru gets to meet and spend time with. He spends time teasing Gokudera, who worships the ground Tsuna walks upon and resembles an angry cat that smokes. He spends time joking with Yamamoto, who, despite the easy-going smile, is sharp as a blade. He spends time with sweet Kyoko, who isn't afraid to throw a punch and bakes the tastiest sweets he's ever eaten. He spends time with seemingly childish, but observant Haru discussing cosplay and such. He spends time with shy, but resilient Chrome who's more than meets the eye. He even spends time with Lambo, who drives him nuts half the time. There are many others, but he did not have the pleasure of meeting them yet.
But most of all, he spends time with Tsuna. They don't talk about the secrets they both obviously have, together they can just be. To her and her — his now too, Tsuna reminds him — friends, he's simply Satoru and not the strongest of the Jujutsu World.
And then… Amanai Riko and Fushiguro Toji happen. Suguru leaves and his world shatters like a castle of glass. He wonders if Tsuna and others will leave him too once he tells them the truth.
Only one way to find out, he supposes.
Sawada Setsuna doesn't know a lot about Gojo Satoru, but since meeting him months ago she likes to think she learned enough to consider them friends. He reminds her of Byakuran in a way: both mischievous, powerful, a little arrogant, like to flirt, and have a notorious love for sweets. The difference between them is that while Byakuran wished to rule the world once, Satoru doesn't want to. It's not for a lack of power — he has more than enough, according to his proclamations of being "the strongest" which ring true to her Intuition — it's more like a lack of motivation. He's more content using his power for other things and being praised for them than being crowned King or God of the world. That, and Tsuna suspects he's already lonely enough on that pedestal of his. He doesn't need godhood on top of that.
Those musings aside, like she said Tsuna thinks she knows her friend and what to expect from him. Only, Gojo Satoru being… well, Gojo Satoru decides to defy those expectations.
"Yo, Tsuna," the voice of her subject of thoughts breaks through her musings as she stands up from the chair to face him in the doorway. Speak of the devil. "Daydreaming about me?"
"In your dreams, Satoru," she says in lieu of a hello. No need to stroke his ego further by saying she mused about him just now. "It's been a while. How have you been?"
"Never better!" he reports cheerily. She narrows her eyes at the obvious lie. It's the same Satoru she knows, but at the same time, he isn't. Something broke in him in the time they hadn't seen each other.
"Cut the bullshit, Satoru," she tells him sternly. "Something happened and you're lying."
"My, Tsu-chan, such vulgar language," her friend chides her playfully, but his heart isn't in it. Another proof something is wrong. "You should stop hanging out with Hayato, he's a bad influence." He turns serious. "But other than that, you're right. Something happened."
"Come in then," Tsuna lets her friend in her room and closes the door after him. Once they are seated, she goes straight for the business. "What it is, Satoru?"
"Wellll," Gojo drawls nervously, causing Decimo to raise an eyebrow in surprise. This is the first time on her memory that self-assured Gojo Satoru, who walked with a swagger in his step, is nervous over something. "I kinda need your help."
"With what?" she asks more than a little confused. What kind of situation happened that Satoru, the strongest as he often put it, needed help from her?
She sees him taking deep a breath, steeling his nerves. Then, he blurts out what she doesn't expect at all: "With raising the kids."