Making the Team/Bring Mary, go home
Despite your twisted feelings and your mind being in uproar, you find that your feet carry you back home like in autopilot. In just the same state you reply to the question of your father if you know where Mary is, telling him that you have brought her over to a friend, the lie coming far easier than you had thought. You only come back to your senses, at least somewhat, when you drop down into your computer chair in your room. That is also when you realize, that you have one major boner in your pants, your cock feeling as if it is ready to explode at the slightest touch.
This is just too surreal and you decide to ignore the urge to wank off, it would feel just too dirty now, with your head filled with whatever the guys are currently doing to your baby sister. You also ignore the knowledge that you have brought her there in the first place and that you are majorly turned on by the whole scenario. Instead of this, you simply turn on your PC and start the first time consuming game you can find and sooner than later you find yourself once more drawn into the world of Skyrim, again. Even after several years it is still a good game and with the large amount of mods you have installed it is a whole new gaming experience anyway. AND you can't yet afford Fallout 4, so you will try to kill the time until that time with Skyrim.
You are only pulled back into the real world, when you hear your phone buzzing, alerting you that you have gotten a SMS. You also notice that it has been hours, five and a half, since you have come back home. Suddenly once more nervous as hell you grab the phone, unlock it and read the message. It's from Jesse, a simply message, "We're done, you can have her back now." Biting your lip, you realize that after you have shoved away the knowledge of what you have done, you must now face reality and make a decision.