A strange sexual costume.

What you see when you open the box is strange. It looks like some kind of erotic costume, though it's clearly intended as a joke. Even it comes with various sexual toys!

Afraid that anyone might see you, you take the package to your room. As you walk down the hall, you hear groans and moans coming from your sister's room, reminding you of your most recent discovery.

Just an hour ago, you found out that your girlfriend and sister are having an affair. What hurts the most is that you were secretly in love with her. Actually, she is not really your sister but your stepsister. Her father married your mother when you were both teenagers. Back then she had the body of a boy. Even if she wasn't your blood sister, she quickly won your affection. You made up your mind to support her through her transition, especially since when she first confessed her feelings, her father had a heart attack and passed away. That fact haunted your sister for a while, making her feel guilty even though both you and your mother tried to convince her otherwise.

Eventually she started taking hormones. She was lucky enough to get an early start, which helped her female body develop thanks to going through puberty. She recently confessed to you and your mother that she was hesitant about removing her genitalia, as she had heard that reconstructions occasionally cause loss of pleasure. "loss of pleasure my ass," you think to yourself. "You just love fucking my girlfriend, don't you? Well, ex-girlfriend now, I guess..."

You quickly walk into your room and close the door, unable to bear the sounds coming from the other room any longer. Who could? It's not very nice to hear your girlfriend beg for more while she confesses that the other dick gets to places inside her that yours never could. What affected you the most when you caught them was that they never stopped. They just looked at you with a guilty expression as they continued fucking.

Now you understand your ex's refusal to have sex recently. She was sated, after all. Those bitches! After everything you did for them, this is how they thank you! Not only did you support your sister throughout her transition, but you literally helped her to talk with your mom since she didn't understand it. You were her cloth of tears every time one of her friends abandoned her. You were her only support for a while too. After all that, she didn't hesitate to fuck your girlfriend.

As for your ex... certainly her betrayal is just as serious. Not just for cheating on you with your sister, which is screwed up in itself, but even then that's not the worst. No, the worst thing is that she almost left you several times because of the way you treated your sister. "No brother treats her sister like that, Chris. You clearly have feelings for her. I won't wait for you to cheat on me, you know I hate infidelity..." You finally even dared to come clean with her and confessed your little crush towards Zoe. Mandy overreacted so much that you feared you had made a terrible mistake. But you both managed to fix it and your relationship eventually returned to normal.

"I'm sorry Chris. I had to find out why you loved her so much. One thing led to another…"

Mandy uttering that apology between moans as she continued to ride Zoe certainly didn't make it anything better. Having your sister comforting her through the whole thing, while she explained Mandy what a wonderful person you are, added to the punch. Especially since they both ended up coming to the conclusion that you would forgive them, all while your stepsister left a nice creampie inside your girlfriend's pussy, which literally squirted everywhere, something she never did with you.

Another scream announces a new orgasm from both of them, audible even with both doors closed. Wiping the tears from your eyes, you begin to check the package, hoping it isn't some kind of weird apology from the two traitors. Or worse, some costume they requested to spice things up between them...