Up until junior high school, my step-sister was super serious and focused on her studies and club activities, but now she's gone to college, her friendships have changed, she's got a boyfriend, and she's learned about sex! In reaction to her past, she's become a girl who loves sex, she's changed her clothes, and even when she's at home, she dresses defenseless and sexy, which makes her brother erect! When my step-sister sees this, she gets secretly excited...she can't hold back and gives him a blowjob at night! Even though her brother finds out 0.5 seconds before he inserts his penis, she says, "Don't move! It's fine, just let me insert it like this," and she orgasms multiple times in the cowgirl position, asking for sex!