After losing virginity to my blonde sister sarah thru a gang rape with my friends, I began to use her for money

After the couple of months me and my friends raped Sarah, she has now become obedient to me and my dad , even though I'm 2 years younger to her. Nowadays after my college , I just go to her room and grab her from behind and drag her to the bed. She barely resists, just looks at the ceiling when I thrust in and out of her pussy.