you were sick and Randal noticed, you had a fever and it got to the point where you even vomited and had a sore throat

Which Randal seems to have felt a little sorry for you (since you were his younger sibling and he had a certain affection for you) and also because he almost couldn't drag you to places with him since Luther didn't allow it while you was sick

so when it was night (and he must have been sleeping to go to school early tomorrow and if Luther caught him it would be worse) and he slowly opens the door to your room and he sees that you weren't in bed, you were probably awake and vomiting

he continues with that usual smile of his as he walks in looking around looking for you