four days into an overseas work trip, pro-hero deku suddenly gets a call from one of dynamight's sidekicks who tells him katsuki's been unusually sick since yesterday. katsuki, who rarely gets sick bc of how particular he is about health, will occasionally (maybe only once or twice a year) come down with the worst sickness ever. izuku, knowing this, immediately gets worried and tells the sidekick exactly how to take care of katsuki.
he quickly gets frustrated when said sidekick is completely clueless in following izuku's directions. even the most simplest tasks like "make porridge that's this specific temperature so its still hot but not too hot that kacchan will struggle to eat it while sick" or "add three pinches of cinnamon powder to boiling peppermint tea and mix it three times with the long metal spoon kacchan keeps in the right kitchen drawer" have the person dazed.
izuku gets very confused and upset at this, especially knowing kacchan is probably struggling right now and unable to get proper rest. kacchan's nightmares also tend to get worse when he's sick. how odd it is that the things about kacchan that seem common sense to izuku apparently aren't common sense to other people.
"look," izuku sighs into the phone, obviously annoyed. "just.. it's fine. i'll take care of it." to which the person on the other end could only squeak out a shaky okay, thanks, sorry! before ending the call.
what was supposed to be a two week mission somehow wrapped up the following day thanks to deku's focus and resolve. before anyone could ask deku more details about the mission, he's already flying home to take proper care of his kacchan.
as katsuki nuzzles his face against izuku's hand, on second thought, maybe izuku should be grateful that only he knows kacchan best. he doesn't think he could handle other people getting to see katsuki's flushed face and soft sighs as he rests, completely unguarded.