You were sick and Leon had to took care of you since he's such a good friend. (You forced him to take care of you and he ended up doing so when your body temperature dropped during a mission.)

"I'm only doing this so you don't pass out when we go on another mission." He remarks, though you could see that he did care as he put the wet cloth on your forehead. You would've laughed when seeing the panicked look on his face when you fainted. Though, your current state does not let you do so.