Chapter Text
"You said you'd be gone by eight."
Nobara Kugisaki, spread-eagled across Megumi’s beanbag like she has claimed it through some ancient rite of conquest, waves a hand. She stuffs her other hand into a chip bag that is resting on her stomach, chewing loudly and deliberately. Megumi does not own chips. He has stopped investigating because the investigation was making him hungry.
"It is eight," she says.
"Eight in the morning."
She had barged in his room at six yesterday, dozing off on the beanbag after binge watching an entire season of Gossip Girl. The show was somewhat entertaining, something that Megumi would never accept.
"Time," she says serenely, "is a construct invented by people with places to be. I have nowhere to be." She opens one eye. "Neither do you, technically."
"I have studying to be."
She snorts. "That doesn't grammatically —"
"It does in this room."
He highlights a sentence about rigor mortis with the measured calm of a man who has made peace with his circumstances, mostly. Kugisaki has been his neighbour since their first year, when she knocked on his door in September with a box of banana milk, said something along the lines of “my roommate snores and I heard you live alone,” and declared them friends. She was right about the friendship, ultimately. Megumi finds this annoying in retrospect. Law students have this power to bend things in their favour.
Her voice has become, over two years of involuntary exposure, a kind of white noise, unnecessarily calming in its own way. Like tinnitus, but with stronger opinions about skincare.
"You're going to be late for your own lecture," he says, because the chip-crunching is beginning to interfere with his ability to retain information about the postmortem interval.
"Covered." She doesn't move. "Maki’s sitting in for me."
Megumi stares at the page. "You have your girlfriend attending your lecture."
"Girlfriend privileges," Kugisaki says, with the specific tone of someone making fun of Megumi’s own love life, but he chooses not to acknowledge it.
He instead turns a page. Somewhere down the hall, someone's alarm is playing a song about love and loss at a volume that suggests they are also deaf. This is simply what Saturdays are now. He has accepted this the way he has accepted many things: quietly, privately, with significant internal resentment.
He has plans for such Saturdays. Not interesting plans, by the standards of people who find things interesting. But his plans involve his Forensic Pathology notes, approximately three cups of coffee, and the accumulated silence of a room that contained exactly one person who was not bothering him. He has a system.
However, this system does not account for the three knocks that echo through his room door.
Megumi looks up from his textbook.
Across the room, Kugisaki goes very still, as if she has been waiting for something and is now experiencing the deep satisfaction of it arriving on schedule. She doesn't sit up. She doesn't look at the door. She simply stops moving in a way that is somehow louder than anything she's done in the last hour. This suggests she knows something Megumi doesn't, which is already a bad sign.
He opens the door. The person on the other side is not, technically, a stranger.
Megumi has a professionally calibrated eye. He notices things. He catalogues them without deciding to, files them without trying to, and retrieves them with an accuracy that has proven useful in Forensic Science and mildly disconcerting in every social situation he has ever been in. It is not a gift so much as a factory setting he cannot locate the switch for.
So yes. He has seen this person before.
Pathology lecture, Monday to Friday, seven a.m., which is either a scheduling oversight by Jujutsu Tech or an act of deliberate cruelty. The lecture hall is not large. There are not enough students in Pathology for anyone to be truly invisible, and yet this particular person has never actually spoken to him, never entered his orbit in any meaningful way.
He has, however, entered his peripheral vision on a reliable basis, because he is — and Megumi means this in the most purely observational, non-complimentary sense possible — impossible to miss.
The pink hair is partly responsible for this. It catches light like it was specifically designed to do so. And then there is the matter of the smiling. Megumi has documented, without intending to, that this person smiles the way other people breathe. At seven in the morning. Laugh booming in the room during a Pathology lecture about cellular death.
And yet here is Itadori Yuuji from veterinary medicine, standing in his doorway at eight-thirteen on a Saturday morning, pink hair catching the hallway light, newly discovered chocolate brown eyes shining earnestly, holding absolutely nothing that would explain this.
Then he waits.
Because there must be a reason. People do not show up at the doors of people they have never spoken to without a reason. Megumi will identify it, address it, and close the door.
"Hi!" Itadori says, with the energy which cannot be harnessed by Megumi ever, even after a million doses of caffeine in his bloodstream.
He says nothing. This is, in his experience, the most efficient response to unsolicited greetings.
The person's smile doesn't falter. Interesting. Most people find the silence at least mildly disconcerting. "You're Fushiguro, right? From Pathology?"
“Yes."
"Great! I'm Itadori Yuuji. I'm also from Pathology." They say this as though it is charming news. As though Megumi has not been looking at them from across a lecture hall for the past six weeks. "Can I come in?"
The correct answer is no. That doesn’t stop Megumi stepping slightly to the side, allowing the man in front to fully enter.
The correct answer was no.
Itadori steps into the dorm room and immediately takes stock of it with the unabashed curiosity of someone who has never been told that widely staring is a form of intrusion. His eyes track across the corkboard, the stacked textbooks, the two mugs, the deliberate absence of unnecessary objects. Then he spots Kugisaki, still on the beanbag, now wearing the expression of a woman watching a scheme pay off in real time. Megumi watches him take all of this in with an expression that is not quite surprised and not quite impressed and sits somewhere interestingly between the two.
"Kugisaki!" Itadori's whole face reorganises itself into delight. "You're here!" He then lets out an audible gasp, wildly pointing at her. “You tried the flavour I recommended!”
"Itadori!" She sits up, gesturing at the chip bag. “It’s an absolute adventure for the taste buds.”
"Right?!" Itadori is already crossing the room, already eating a chip she has already extended toward him, already fully absorbed into a conversation that has consumed the entire scene. "The aftertaste is the whole thing. Most people give up before the aftertaste."
Megumi stands by his open door, effortlessly forgotten.
The pieces assemble themselves in Megumi’s head as the conversation progresses.
Kugisaki. The chips that were not hers, which means she brought them, which means she planned to be here for a while. The three knocks that sounded as the comfortable rhythm of someone who had been expected. And now this specific person from this specific class is standing in his room with a smile that appears to have been manufactured without an off switch, eating Kugisaki's chips, discussing chewing speeds, behaving as though his dorm room is a location they naturally spawned in.
Megumi looks at Kugisaki, who conveniently focuses on the pig-like water stain on the ceiling.
"She's the mutual," Itadori says, apparently concluding that the chip conversation has reached a natural pause and turning back to Megumi. "I needed help with Pathology — not like a little help, it's sort of a —" he makes a gesture that implies structural collapse, "— situation. Kugisaki said you were the smartest person he knows."
"Genuinely the smartest," the said person confirms, still staring at the ceiling.
"So she said I should ask you to tutor me." He clasps his hands. The smile remains bright, aimed at him like sunlight through a lens. "So I'm asking you to tutor me."
Silence fills the room again. It is Megumi’s silence. He built it. He is comfortable in it.
He uses it now to regard the situation with the detachment of someone reviewing evidence. Unknown person in his dorm room. Orchestrated appearance facilitated by Kugisaki, who will be receiving feedback on this later. Request for personal academic interaction. With a human he does not know. In the time and space he has specifically designated for not interacting with humans. Except Nobara, who Megumi now firmly believes is not a human, but an alien sent from Mars.
In the adjacent dorm rooms, people are living their Saturday lives. Somewhere, a kettle boils. Megumi’s corkboard index cards hold their ground. His textbook is still open to page 214. His coffee is still at an acceptable temperature. The world is full of things that are not this situation, and he would like to return to them.
He glances at Itadori again, who’s wearing the look of someone who has not yet considered the possibility that the answer could be no. Megumi feels it’s mostly arrogance, with hints of optimism.
He still has the toothy grin plastered to his face, eyes shining with determination. Megumi sees it everyday. It is not uninteresting.
But it is also not his problem.
"No," he says.
Itadori blinks twice, processing the rejection. The smile remains, but readjusts with uncertainty. "Sorry?"
"No." He says it the same way for clarity. "I don't know you. I study alone. That's not going to change because you need a tutor."
"Kugi said —"
"Kugisaki," Megumi says, turning fractionally toward the beanbag, "is a person I allow in this room because I have accepted that she cannot be completely eradicated."
Kugisaki, to her credit, does not argue. She does eat another chip.
Itadori opens his mouth, then closes it. It is the first time since he appeared in the doorway that he seems to be genuinely searching for a response, and Megumi recognises this as the appropriate moment to consolidate.
"There will be tutors at the library," he says. "The university also has academic support services. Both of those are better options than me." He takes a step back. The universal language to mark the conclusion of this conversation.
Itadori looks at him for a moment that is two seconds longer than necessary. Megumi almost accepts the proposal, but his disdain towards the human population weighs more than the intensity of coffee-coloured eyes he now finds are pretty enticing.
Then he smiles again, but not in the usual manner, and nods once.
"Okay," he says simply.
And that, Megumi thinks as he closes the door, is the end.
He goes back to his desk. His textbook is still on page 214. His coffee is still warm. His index cards are still colour-coded and exactly where he left them.
Kugisaki does the correct thing and shuts up.
Back to normal.
The results go up on a Wednesday.
Megumi knows this because Gojo Sensei emails at precisely 2:43 a.m. with the subject line "Surprise Assessment Results: please review :)". The smiley face is doing a lot of work in that sentence, specifically the work of a man who finds other people's suffering personally entertaining. This is not a new development. Professor Gojo has been finding things funny at his students' expense since the first lecture, when he walked in fifteen minutes late wearing sunglasses indoors, had dramatically announced that Pathology was "basically a love story between the body and everything trying to kill it," and then had employed Arts’ students to enact a retelling of Romeo and Juliet. He is, by every measurable metric, an immature infant. He is also, infuriatingly, the best professor in the department, which he knows, and brings up repeatedly in every single lecture.
The test had been announced with the cheerful spontaneity of a man who had absolutely nothing to lose. Megumi respects the academic competence. He resents everything adjacent to it.
He also resents that the surprise was functionally wasted on him, because Gojo Sensei cannot keep a secret, and had blurted it out in the morning before. He finished twelve minutes early and spent the remaining time identifying errors in the question formatting.
He opens the results on his laptop. Scrolls to the top.
His name is there. First, which isn’t surprising. He closes the tab. Stares at his home screen for forty seconds.
He really shouldn’t do this.
After careful calculation of his next step, he reopens the tab. He scrolls past the solid performers, past the middle cluster, past the students who clearly skipped Chapter 7. Further down, into the territory of the list that gets quieter and grimmer the further south it goes —
Second from the bottom.
Itadori Yuuji. 34 out of 100.
Ahead only of one Inumaki Toge, who got 29 and who Megumi vaguely recalls putting his pen down with fifteen minutes left, blankly staring at the ceiling.
The class average is 62. Megumi's score is 97, missing three points. He had deliberately skipped the last question, titled “write the best attributes of Gojo Satoru.”
Megumi looks at it for approximately four seconds. Then he closes the laptop, picks up his bag, and leaves for class. Stops thinking about it at all, because it’s irrelevant and unimportant.
The walk to the shared curriculum building takes seven minutes. Megumi knows this because he has timed it on four separate occasions under different conditions, and averaged the results. He arrives at the Pathology lecture hall at 6:52 a.m., eight minutes before it begins, and takes the seat he always takes. Back left. One from the wall. Clean sightline to the board, sufficient buffer from the aisle to avoid being spoken to by people moving through it, far enough from the front to avoid being voluntarily selected for demonstrations. The hall fills the way it always fills, and at 6:58, the door at the front swings open.
Professor Gojo enters. He is wearing sunglasses, as usual. There is a running theory among the students that he sleeps in them, a counter-theory that he doesn't sleep at all, and Megumi finds both plausible. He sets his coffee down, drops into his chair, spins it once for no reason, and faces the class with the bright, unthreatening smile of a man who is about to say something that will either be inappropriate or insulting.
"Morning, you uglies! Big day today. Homeostasis. Who read?" He scans the room with the evaluating look of someone who already knows the answer and is asking purely for the entertainment of watching people decide whether to be honest. Three hands go up. He points at each of them with finger-guns.
Megumi's hand is not among the three. He read. He simply does not raise his hand, because then Gojo Sensei will probably invite him up in front of the class, telling everyone to clap for him, because during his first year, he had caught the great Gojo Satoru’s eye.
6:59 becomes 7:06, and the lecture finds its footing. Gojo draws a cell membrane on the board, which is the ugliest diagram Megumi has ever seen, narrating as he goes with too much energy. He makes a joke about ion channels that lands for roughly four people. He seems unbothered by the ratio.
Megumi is two paragraphs into his notes when the door opens.
Gojo doesn't even pause his diagram. He simply says, to the board, already expecting:
"Itadori."
"Professor!" The voice comes from the doorway, slightly winded, "Good morning! You look great today."
"I look great every day." Gojo turns around. He is smiling in the way that suggests he finds this person specifically delightful, which is arguably more dangerous than finding them annoying. "You're —" he checks his watch theatrically, "— sixteen minutes late! Not bad."
"The vending machine on floor two took my money and then just stood there."
"Did it now?"
"I pressed the button. Nothing happened. I pressed it again. Nothing. I had a whole moment with it, Sensei, I had to process."
"And how long did processing take?" He finishes the traumatic diagram, turning to look at Itadori.
"...Sixteen minutes, roughly."
Gojo opens his duffel bag, ignoring the other twenty-one students waiting for him to continue teaching, and removes a bag of chips. He then hurls it at Itadori with alarming force, who catches it with ease.
“If you ever need a snack, tell me.” Gojo returns his gaze at the board. “I will buy it for you.” He reaches over to ruffle Itadori's hair, who accepts it with numerous words of gratitude.
Gojo continues teaching, and Megumi takes notes. He watches Itadori moving towards the seats through his periphery. Sees him skip eleven free seats in the front row. A few more in the middle rows. He keeps walking up, and Megumi almost believes –
Itadori sits beside him comfortably, eyes locked on the board. He does not, immediately, say anything.
Megumi is quite surprised by this, and half-impressed because it’s a more sophisticated opening than anticipated. He had prepared some defence strategies against the unnecessary greetings, the bright smiles, the immediate verbal extension of the same social butterfly that had appeared in his doorway on Saturday. Instead, Itadori settles in, extracts a notebook from his bag, uncaps a pen, and faces forward. It almost seems as if he is absolutely, completely, not doing anything deliberate.
But the smirk he is trying to hide fails him. It’s not entirely there, but still noticeable. Megumi looks at it for exactly one second. Then he looks back at his notes, because he is here for Pathology, and the person sitting to his left is not a variable he is obligated to engage with, and everything is fine. A peaceful minute passes.
"What are we doing today?"
The question is quiet enough to technically not constitute disrupting the lecture. It is also accurate, as Itadori arrived late and wishes to know what all he missed. But that doesn’t stop the scowl sitting on Megumi’s face. He waits for the question to dissolve into the ambient noise of the hall.
But he can feel Itadori’s puppy-like eyes on him, patiently waiting. Megumi decides to reply, just to peel that stare off of him.
"Homeostasis," he says flatly. An appropriate, one-word response. The question was asked, the answer has been given, the interaction is now complete and can lapse naturally into —
"What's that?"
Megumi's pen stops.
He looks at his notebook. The ink dries mid-word. He completes the word, because incomplete words start an uncomfortable itch in Megumi’s brain.
"A biological process," he says. "The body's system for maintaining internal stability."
"What kind of stability?"
"Temperature. pH levels. Fluid balance."
"So the body's just," Itadori’s eyebrows knit together, "constantly correcting itself?"
"That's the mechanism, yes."
"Huh." The class lulls into the same silence before Itadori’s existence, and Megumi is relieved. He uncaps his pen, writing keywords in the margin —
"What's he drawing on the right side? I can't see from here."
Megumi looks at the board. "Negative feedback loop."
"Which is —"
"A regulatory mechanism," Megumi says, now opting to give short answers, whatever would stop Itadori’s question, "where the output of a process signals back to reduce that process. The body uses it to self-correct. Temperature rises, the loop triggers cooling. Temperature drops, it triggers warming."
Itadori props his chin on his hand, turning halfway towards Megumi. "Like a thermostat."
Megumi frowns. “Yes. That's accurate."
"I understood something." Itadori says quietly, but his eyes shine with delight. Megumi feels the happiness is a bit of a stretch, that too over the achievement of understanding a thermostat analogy.
"Okay, what did I miss before I came in? Like the first part." Itadori’s voice is more unrestrained than before, enthusiasm leaking in every syllable.
"The cell membrane. Basic review. Nothing that won't come up again."
"Will it come up today?"
"Tangentially."
"I don't know what that means."
"It means," Megumi drawls, "related but not central. You'll follow it."
Itadori definitely didn’t understand the meaning.
"What if the thermostat breaks?"
Megumi's pen slows. This is, marginally, a better question than the previous several. He finds himself answering it before he decides to. "The system doesn't break cleanly. It fails by degrees. In fever, for example, the hypothalamus resets the target temperature upward in response to infection. The regulatory system is functioning correctly. It's just aimed at the wrong number."
He feels Itadori think for a while. "So it's not broken, it's just wrong."
"That's one way to say it."
"The thermostat thinks the house should be on fire," Itadori says, a satisfied tone suggesting he thought he nailed something.
Megumi writes a sentence which isn’t related to Itadori’s questions, but the actual topic of the day. "That is a significant oversimplification."
"But is it wrong?"
Megumi exhales. "...No."
"Okay." He writes something down. Then, four minutes later, in a completely different segment of the lecture: "What's a cytokine?"
"Signalling protein. Coordinates immune response."
"So it sends messages."
"Essentially."
"To who?"
"Relevant immune cells. The hypothalamus, in the context of fever."
"So it's like —" Itadori pauses. Megumi can feel him arriving at something. He waits for another stupid analogy. "It's like a group chat. For the immune system. The cytokine sends a message, everyone reads it, the hypothalamus resets the thermostat, and the body starts running hot."
Megumi hates how it makes sense. "I'm not," he says carefully, "going to validate that framework."
"You don't have to." Itadori is already grinning wide. "I'll remember it either way."
*
The class ends at 7:50.
Gojo closes his laptop, spins his chair again, and announces that next week will be "even more fun, which I know you're all thrilled about" which is more of a threat, really. He dismisses the class with a wave, and dashes out the class at the speed of light.
Megumi caps his pen and closes his notebook. Slides it into his bag in the correct section, behind the correct divider. He stands without acknowledging the man previously sitting beside him. He has Forensic Biology at eight, and the building is a nine-minute walk, and Chapter 6 is waiting on his desk. He happens to look left, and the looking is a coincidence of timing that he cannot be held responsible for.
Itadori is looking at his phone.
The academic portal. The page is visible, and the name on it is visible, and the number beside the name is visible, and the face looking at the number is —
Megumi stares at him for three seconds.
Three seconds of a face that has stepped outside its own performance. The specific stillness of someone doing quiet calculations in their own head and arriving at an answer that sits heavier than expected, and holding it there, in the three seconds before awareness catches up and covers it over again with something more manageable.
Megumi has seen that look before. Not on this person. On himself, in a different semester, over a different subject, around 2 a.m., in the mirror above the bathroom sink. Before he found the method that worked.
He should leave. He has Forensic Biology at nine. He has Chapter 6. He has a system, and the system works, and the system works specifically because it contains exactly one person and that person is not Itadori Yuuji.
He stands in the aisle. But something forces him to stay there, feet unable to move. He remembers bright smiles and deep brown eyes, holding hope, something he never would be accustomed to.
Three seconds of a face. Megumi exhales.
"Itadori."
The phone disappears into a pocket immediately. The smile is back, operating at a slightly reduced wattage but fundamentally intact. Megumi’s heart twists. "Hey. Was I too loud again? I can —"
"No."
Megumi looks everywhere but directly at Itadori. Looks at the awful diagram on the board. A sparrow perched on the windowsill. The empty seat beside him.
"Your score," he says.
Itadori’s smile falters, simmering down. "Yeah." He glances at the pocket where the phone is. Then looks back up. "It's fine. I'll do what you said. About the academic services, or something.”
“Don’t.”
He shouldn’t be doing this. This is way out of his expertise, out of his timetable, and he won’t be able to handle it. This has numerous downsides. So many negative outcomes, which will ultimately —
"Fushiguro."
He stops.
"Are you," Itadori says slowly, the gleam in his eyes returning, "offering to tutor me?”
He is. He is apparently doing exactly that, which is something he explicitly told he wouldn’t do on Saturday, with words, out loud, directly, and has now arrived at anyway through some unmonitored back corridor of his own reasoning, which he would like to locate and close. He sits back down, placing his bag on the ground.
"There are conditions.”
He can see Itadori trying his best to hide the smile tugging his lips. "Okay."
"I'm not saying them twice."
"Understood."
"And if any of them are broken,” Megumi opens his notebook to a blank page at the back, because verbal agreements about structured arrangements are an inefficiency he refuses to participate in, "the arrangement ends. Immediately. Without renegotiation."
“Got it!” The default brightness is back on Itadori’s face. “Hit me.”
Megumi uncaps his pen.
"First," he says, and writes it down. "Don’t be late."
"Easy."
Megumi looks at him, raising an eyebrow. Seriously?
"...Okay, it's not easy," Itadori corrects, because he’s incapable of sustaining a bluff for longer than three seconds. "But I'll do it."
"Not one minute late. Not thirty seconds late. If the session is at ten, you are present at ten. Not arriving at ten. Present."
"That's —"
"Second." He writes. "Bring your own materials. Books, notes, stationery, whatever. I'm not a supply depot."
"I have a notebook."
Megumi glances at the desk. A thin, colourful notebook is occupying the space, and it seems to be the only one he has. "That one is fine. Third." He writes. "No conversation unrelated to Pathology during sessions."
Itadori pauses. "Define unrelated."
"Anything that is not Pathology."
"What if something seems unrelated but is actually —"
"It isn't."
"You don't know what I was going to say."
"It isn't," Megumi repeats, and quickly continues before any follow-ups. "Fourth." He writes. "Read the required chapter before each session. Not the morning of. Before. With enough time to arrive with specific questions."
"Yeah. I can do that."
"I won't explain things twice," Megumi caps his pen. "Sessions are for clarification and application. If you haven't read, the session doesn't happen."
Itadori nods vigorously, smile unmoving.
Megumi looks down at the page. Four conditions, numbered, clearly written. He tears it out along the spiral edge, and sets it on the desk between them.
“So,” Itadori exclaims giddily, “That’s it?”
“Yep. Four conditions.”
He picks up the page, folding it carefully and preserving it in the front pocket of his bag. “Let’s do this.” Megumi feels that he should remind him that this isn’t a fight.
He picks up his bag, standing upright. "Monday," he says. "Chapter 5. Read it."
"Monday," Itadori repeats, and Megumi has never seen someone so excited about a weekday before.
They leave the lecture hall together.