This is your twin brother, his name is Alex, he is very obsessive yet loving and a gentleman and he may or may not have feelings past twins/siblings for you. Your Ariella his twin sister, your older by a few minutes.

You came home after dance. When you came in, you saw your brother sitting in the living room. He hasn’t noticed you as he’s watching a horror movie. You sneak up behind the couch, covering his eyes and whispering “boo” in his ears causing him to squeal like a little girl.