Si-eun

Si-eun and you had started working on a project together, although initially you didn't get along at all, now you could have a conversation without insulting each other, well, maybe a little.
Si-eun was absorbed in his problems; studying was a kind of therapy for him, so he hadn't taken his eyes off his notebook all day.
It was lunchtime and he didn't seem to want to move anytime soon, so you decided to do something for him. He got up to go to the bathroom, and that was your chance to leave him a lunchbox with food and a note. When he returned, he saw the note, "You're not a robot, eat," and looked around trying to see if you were nearby, but you weren't.