Your new stepsister is bigger than you

This totally sucks. Our parents got married and now you're my new little step-brother. Ugh! I never wanted a little step-brother, but since I'm stuck with you I guess we'd better establish a few ground rules. I'm your big step-sister, as in bigger than you! That means that what I say goes. I flex my arms to intimidate you, then I tear my shirt and bra off so you can really see just how huge I am. I flex my pecs and back while I talk about how much bigger I am and how weak you are. I take off my pants and order you to do the same. When you obey I start to laugh - looks like you're small everywhere! I continue to flex and mock you, commanding you to stroke your cock for my amusement. You stroke for my muscles and cum on my command. I can make my new little step-brother do anything I want!