Emma helps your sister practice anal sex.

While you return to your regular life (well, as regular as it gets with a devoted slut like yours), Emma takes time out of her busy day to meet with your horny sister. She's started doing her own research, getting a sense of how to relax her asshole for a little while before sex, take deep breaths and go slow at first until she's comfortable, but Emma knows that won't do.

"Oh, I'm so sorry, but that's not how John likes to fuck. If you really want to please him, he has to fuck you like a caveman." Emma hangs on the last word, letting the imagery flood your sister's horny head. Her hair entangled in your fist, her mouth gasping and wailing, you marking your territory over her body however you want, wherever you want. Your sister grew up hearing you fucking your many high school conquests in the room next to her, leaving them whimpering as you finished and let them clean up.

Emma tells your sister that she has to become enough of an anal pro that she can handle the pain of you going in hard immediately. She stresses that it won't be easy, but your sister, although nervous, is awash with perverted hormones and knows that if she practices, she can endure anything to be with you. Your girlfriend agrees that they can start slow here, but they'll have to ramp it up.

Over the next few weeks, Emma gets very acquainted with the taste of your sister's asshole, lubing it up generously with her tongue every day. This is the only preparation your sister gets before Emma selects one of her sizeable dildos (the ones she uses when you aren't available), and takes your sister for a ride. At first, it's discomforting and stressful, but slowly your sister learns to focus on the pleasurable stimulus and relax herself enough to stretch around the huge silicone toys that your girlfriend keeps around. Emma makes sure to set a good example for your sister, too, and shows no compunction about pulling the dildo out and sucking it, before lending it to your sister for a taste. She knows how you like to change things up.