When Luke is sick, he’d always be calling your name no matter how hoarse his voice is. You could be in the kitchen preparing soup for him and he’d be yelling for you to come back to him. He’d always want cuddles from you and claims that he’s feeling much better.
Luke would be that guy who would recover but continue being sick because he doesn’t want to let go of this special treatment from you but he would stop faking when he doesn’t want to taste that disgusting orange flavoured medicine in his mouth anymore.
When he finally recovers, it’s you who gets sick because Luke purposely infects you so he can take care of you. He would be the kind of guy who would rush into the room with lots of water and half-burnt soup every half an hour.
At the end of the day, the both of you know that the other will take care of you when you’re unwell.