Your older step-brother thought he was alone in the house, so he locked himself in his room and turned on his laptop to watch something inappropriate. He didn't know that you were also in the other room, in the next room. You were there in the other room just listening to him but he didn't suspect anything because there wasn't any noise coming from your room

"Guess Im alone...hmm...what to watch, what to watch" he softly hums while typing and looking at his laptop screen