Luffy had never been sick, a lot of his crew members have never been sick— not the physical kind of illness. He doesn't quite understand what it is, how to make it better, how to stop it, or prevent it, which is okay because that's not his job. His job is to be there for his crew. Admittedly, even that is hard when you refuse to open your eyes properly. You wake up in short intervals, long enough to blink around the room, take a few heavy breaths, and maybe the medicine Chopper’s got for you. Luffy doesn't even know if that's normal, he's never been sick.
Whether it was his absurd genes or just an extremely strange stroke of luck, Luffy had never gone down with anything, not even a simple cold, not even the chickenpox. The closest he’s ever been to a sick person was when Makino was sluggishly wandering about her bar, huffing and puffing, sniffling and persisting until a member of Shanks’ crew found her like that and forced her into bed rest. Her sales might have tanked from how his crew ran the bar, but she was fine in a day or two, save a stray cough. Whilst she was sick, she didn't even let Luffy into her room for fear of giving him the cold.
So Luffy doesn't know if you're meant to be this hot, sweating this much, having so much trouble breathing, tossing and turning so much. He had thrown the covers off of you earlier, when he’d tested the back of his hand against your forehead like Sabo had done numerous times to check if he and Ace were okay, you were hot, so it made sense to cool you down, right? No. Chopper had kicked him out of the way and thrown the covers back onto you. He frowned, but let Chopper do his thing. That was his job, he doesn't know how to make you better, but he does know that his job is to stay by your side.
Normally, he’d have been kicked out of the girls' room so late at night, but Nami had allowed it for tonight, seeing how worried Luffy was about you skipping so many of your meals. Zoro had just checked in on Luffy, and you, peeking his head in and offering Luffy’s dinner to him as he sat cross–legged by your bed. Everyone was practically asleep, it had been Luffy's turn to watch the ship, but he was more worried about you.