What if sakusa's parents and siblings were too busy to deal with him, so when he got really sick in the middle of the night, he went to his parents' room for help

But they kind of shooed him off saying he needs to sleep it off, he'll be okay, but he didn't know where to sleep

Because he was sick in his bed and he was crying from how gross and unhygienic it all was.

He tried to wake up one of his siblings but they had an exam the next day, so they werent happy about wrangling their sick, weeping younger brother.

Sakusa ended up sleeping on a spare futon mattress because nobody bothered to clean him up and comfort him. But he didn't think much of it because he was too ill and tired to care. So when he heard about Atsumu getting comforted by Osamu after getting the flu, he was confused.

At first, he insisted Atsumu was 'weak' for needing support when he should have taken care of himself better. But really, he was repeating what was drilled into him years ago. He was jealous of Atsumu. And admitting it was something that took weeks to manage.

The next time Sakusa gets a cold, everyone is there to give him comfort and little gifts. He's weirded out, but happy. And definitely less lonely.