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“Type one pneumocyte.”
Megumi is lying on his side, head resting on his arm as his front sticks to Yuuji, while the other lies on his back, tucking his hands behind his head. They’re in bed, having somehow migrated naturally from Yuuji’s desk earlier, adjacent to the bedroom window that allows the afternoon sun to brighten the room. The light hits Megumi’s eyes just right, emerald green shining brightly in their element.
Megumi’s a little glad that he sent his partner to the showers the moment they came back.
With his eyes glued to the ceiling, Yuuji asks, “Aren’t they called alveolar cells?”
He relishes in the way Yuuji’s voice rumbles inside his chest, feeling the soft vibrations from where they’re glued together, his other arm strewn over Yuuji’s belly. Megumi responds, “That too, but the textbook indicated that ‘pneumocyte’ is fine.”
“Alrighty, then. Type one pneumocytes are for simple diffusion of gases, thin with a large surface area for efficient diffusion. Also super permeable.”
“Which particular gases?”
He feels before he sees Yuuji turn and stare at him.
Megumi blinks, “What?”
“Babe, you can’t be serious.”
“I am serious,” Megumi says as he moves his hand down to Yuuji’s side. He smiles inwardly when the other flinches at the light touch. Yuuji was notoriously known to be a ticklish fuck, always jerking slightly whenever he received jabs left and right from their friends in school.
“Answer me seriously, or I’ll tickle you.”
“You wouldn’t—!” Yuuji yelps, twisting his body away the moment Megumi’s fingers dig into the area beneath his ribs. “Argh, Megumi!”
Megumi raises an eyebrow, prompting him to answer. The other hisses, “Oxygen and carbon dioxide, holy shit. Never do that to me again.”
Megumi, ignoring him, hums loudly, “And type two pneumocytes?”
“Fuckin’…” Yuuji heaves a loud sigh, rubbing the heels of his palms into his eyes. His heart still races in his chest from the unexpected “attack”, cursing his boyfriend internally. He mumbles, “It produces a type of surfactant to dissolve atmospheric oxygen, to facilitate diffusion for type one pneumocytes and make it easier for the…the haemoglobins in red blood cells in the capillaries to bind to. Is that right?”
“That’s right,” Megumi affirms, before angling his face slightly to capture Yuuji’s lips, catching him completely off guard. He lifts himself away before Yuuji can retaliate or send them into another bout of sucking each other's faces, pushing himself to sit up and lean over Yuuji.
“Megu–” A finger lands on Yuuji’s mouth. Megumi smirks at him, “Ah, ah. Let’s do blood transportation.”
Yuuji groans loudly, starting to trash around theatrically on the bed, like a child being refused candy. His movement does nothing to deter Megumi’s evil wish to corrupt him with nerd terms that he believes he truly doesn’t need in the near future(aside from the upcoming examination—or as Yuuji liked to call it, impending doom). There’s honestly nothing cute about this childish act, but Megumi keeps his mouth shut lest he says something to unleash his inner beast(an even worse version of this current whinger, which Megumi really doesn’t want right now).
“Yuu.”
Yuuji begins seizing—no, he’s alright, he’s just faking it because he thinks it’s funny—jerking back and forth, a split second later he pretends to choke himself the same way that one GIF-meme of the white girl does to herself in her car.
The ravenette rolls his eyes.
“Yuu.” He gets Yuuji to stop mid-action. “I’ll give you a kiss for every point you get correct,” Megumi offers, poking Yuuji on the side for a last measure, stifling his laugh when the other jerks again. “Not to guilt trip, but I’m only here to help you with biology, which you’re painfully failing. I still need to cover two more topics for psychology.”
At that, Yuuji finally stops his ministrations. He flops still onto his back, chest rising and collapsing quickly.
His face now harbours the most blank look Megumi has ever seen in a while, and he smiles at Yuuji gently.
“Right, cause your big brain decided you needed to take 20 more courses,” says Yuuji.
“You’re really cute when you’re not acting like a total fucking baby,” Megumi purrs.
“Well, thank God you’re not dating a total fucking baby, that’ll put you on some list or something…I’m JOKING.” He yelps as he spots Megumi’s fingers near his sides in his peripheral vision. Yuuji huffs, “Omg, fine. I’ll lock in now.”
“Stop saying corny shit like that out loud, you’re gonna embarrass us one day.”
“Nothing is embarrassing when I’m with you, baby,” Yuuji mumbles in a failed-flirtatious way. It forces Megumi to tilt his head back and stare at the ceiling, feeling his resolve slipping. He inhales deeply.
Yuuji takes it as a sign to get cracking before his boyfriend genuinely leaves.
“Okay. Um. Blood moves through the body, then through the heart and out, then towards the lungs for gas exchange, and through the heart and back out to the body—Now give me a kiss!”
Just as Yuuji basically launches himself onto the other, coming just shy of his lips before Megumi slaps a hand directly across Yuuji's mouth.
“That was one out of the seven points you needed.”
Yuuji groans loudly.
“Deoxygenated blood from the body flows from the superior vena cava into the right atrium,” He pauses, trying to remember an acronym he learned from a reel a while back. He mumbles, “TPMA. Toilet, paper, my, ass.”
From where he twirls a strand of Yuuji's pink hair between his fingers, Megumi mouths a bewildered “What?”.
Then, Itadori begins listing, “Tricuspid, Pulmonary, Mitral? and Artrial.”
Megumi realised he was listing the names of the atrioventricular and semilunar valves. “Did you mean aortic?”
“Probably.”
“Proba—” Megumi stops himself. It’s okay, everything is okay, his boyfriend is a little stupid and that’s—
“Which valves are categorised as atrioventricular?” he asks exasperatedly, peeping down at Yuuji’s face. He has his eyebrows furrowed, eyelids shut tightly.
“Yo, what’s atrioventricular?”
This is NOT okay.
“Anyway!” Yuuji exclaims as he somehow miraculously dodges an attempted smack on his shoulder from Megumi. “The tricuspid valve opens, allowing the deoxy-blood into the right ventricle. The TV closes, and the pulmonary valve opens up, allowing blood to flow out of the heart through the pulmonary artery towards the lungs. There, gas exchange occurs through the whole pneumo-alveoli thing. Blood comes back oxygenated and through the pulmonary vein, into the left atrium. The mitral valve opens, allowing the blood to move into the left ventricle. MV closes, aortic valve opens, blood flows out the aorta.
“Also semilunar are the valves before that prevent backflow as blood is transported out of the heart, atrioventricular are the valves separating the blood from atria and ventricles,” Yuuji finishes smugly, the smirk tugging on his lips arrogantly. He looks at Megumi expectantly, who doesn’t make a move other than nod at him.
“Good,” says Megumi.
“That’s it?!”
Megumi hums, “You obviously knew what you were talking about, so it would be redundant to give you a…let’s say, a reward. Let’s move on.”
Yuuji doesn’t seem to take that as an answer because he reaches upwards, wounding his arms around Megumi’s neck to tug him downwards, taking him by surprise. Megumi gasps, throwing his arms out to stop himself before Yuuji accidentally breaks both their noses from the ‘fall’. Meeting his eyes, Yuuji chirps brightly, “I can tell you’re fighting against yourself, Fushi. C’mon, don’t resist.”
“Maybe,” says Fushiguro, shrugging his shoulders. “We really need to finish the transportation topic, though.”
His words fall on deaf ears as Yuuji propels himself up and kisses him square on the lips. A light peck, that nonetheless sends sparks flying behind Megumi's eyelids.
“Or, we can do that after dinner,” Yuuji suggests, mumbling against his lips. Megumi often doesn’t call himself weak, because he really isn’t. But that almost always does a 180 degree turn whenever it comes to Yuuji. Keyword: ALMOST.
Megumi decides psychology and god-forsaken Martiner, Kesner and their stupid acetylcholine can go fuck themselves when Yuuji presses into his lips again, which he reciprocates to almost immediately.