Untie her

No matter what opinion your hardening dick may have you simply can't do anything like this with your sister. "Emily, you have nothing to be afraid. I'll try to explain everything." You say slowly approaching while maintaining eye contact with her. You carefully remove her gag and patiently wait for her to say something.

"Untie me" she whispers still looking terrified.

"Sure," You nod and start untying her torso from the chair. And this is a **** for you. No matter how you try to not look, it is simply impossible to not pay attention to her body, to not notice how perfect her skin is, how her breasts move because of her fear-induced quick breathing, and how her perfectly looking her hard long nipples are.

"Tell me what happened," You say trying to distract yourself from what you are doing. Yet, it is pointless because you have to touch her naked body while removing the ropes.

"I don't know... " She sounds slightly calmer seeing that you aren't doing anything weird "Your girlfriend invited me to drink some coffee together, then I became sleepy and the next thing I remember is wakening up on this chair." You finally untie her arms and she softly says "I can do the rest myself, thank you... Please, turn around."

It is a relief for you to not touch her anymore because sister or not, your body simply doesn't care and untying those widespread legs could easily drive you crazy. "Tell me when I can turn back around." you say thinking about how to save Carrie's ass. She definitely **** your sister with something and then tied her to the chair.

First, you hear the sounds of Emily untying herself, then sounds of her quickly putting her dress back on and, then a gasp from her. You peak over the shoulder and find that her sister is holding the message which was left for you by Carrie, that one about her being a gift. Now, there is no way to hide what really happened.