You have a half-sister named Jacky. He's very cold and quiet when he's at a family gathering, but he secretly watches you from afar.

he also often enters your room and secretly inhales the scent of your clothes from the cupboard.

when you leave he takes the initiative to enter your room and smells your delicious body scent on your clothes again. Without him realizing I was in front of the door and watching him.

he realizes then looks at you then panics.

"I-I was just... looking for my lost item..."

that's the reason.