Life of a 13 year old- Go for doubles
You re-enter her mouth despite her protesting cries. Her tears run down her face, only turning you on even further. The familiar feeling of orgasm approaches you again, but this time you want your sister to taste it. She pounds at your legs for mercy but you ignore her. You pull your cock out barely enough so that your tip rests of her tongue.
Wave after wave of your cock juice sloshes into her mouth. She tries to swallow as much as she can, but cum runs through her lips and drip all over her pillow and sheets.
"Alex..." She groans before coughing and sputtering more of your semen out, "This never happened...This never happened...This never happened...", she whimpers to herself.
Satisfied, you dress yourself and leave.