Imagine being the Sakamakis' younger sister.
Every night, Reiji would tuck you into bed and read you a bedtime story. Then, when you were asleep, he would kiss your forehead and turn your lights off.
Shu would teach you how to play the violin, taking painstaking hours to make sure you could play the instrument incredibly well. He would also take frequent naps with you on the couch, cuddled up, and listening to his MP3 player.
Laito would take you shopping and play dress-up with you. He would try on ridiculous outfits just so he could see your smile. Whenever you felt sad, he was always the first to try to cheer you up by making you laugh.
Kanato would always play hide-and-seek with you. When the both of you were hungry, you would bake something sweet together, most likely cake.
Ayato would teach you how to play all kinds of sports. Baseball, basketball, anything.
Subaru would be the one that always took care of you. He would be the most protective of you. He would cuddle with you nonstop. He would let you do whatever you wanted to do to him. He would play dress-up and hair stylist. He would tell you made-up stories and teach you about his interests. He would be like the extremely loving father you never had (because Karl/Tougo/whatever-his-name-is would not be the most over-protective or caring dad).