It's your "little" sister

"Are you still here?" She asks, entering the house with shopping bags "Don't you have your own place or something? Can, you, please get out?" She is little too rude even for her usual attitude and that makes you wonder what's wrong.

"Sis, it's still my home, too. I am not going anywhere unless you give me a good reason too." You answer and notice another strange thing she bought quite a lot of food, considering that dad is out of town that's strange.

"No, It's my home and your room is taken by Sara. By the way, where is she? " She asked like she didn't expect Sara to be gone, another strange thing.

"Oh, she went clubbing." You answer hiding your nervousness "So my room is mine. Besides, I see you're preparing for a cooking session, I do miss how you cook."

"It's not for you!" She barks.

"Then for who? " You ask.

She sighs "I'm an adult woman. I invited a friend over today. So please, get out. We'll need some privacy." The tone she used seemed to imply that they are planning to have a sex. And the truth is, that doesn't fit your plans, as you want her cherry for yourself. You decided that you should do whatever possible to keep your sister's chastity... For your own use.