She pulls out?!

Just when you expected your womb to get filled, you suddenly feel a empty sensation in your lower body. Confused you look down and see your sister's cock, conspicuously outside of your vagina, right as she ejaculates. With your hands still bound, you can't protect yourself at all as Gwen shoots rope after rope of semen across your stomach, breasts, and face, some even landing in your mouth.

"F-fuck... that was close..." she pants. She glances up from her cock to you, admiring her handiwork. Several thick lines of her seed streaked across your otherwise pristine breasts, covering one of your stiff nipples. There were more streaks of cum across your belly, with some pooling in your navel. Finally, there was a big line of cum across your face, ending in your hair, with some pooling around your mouth. Without your hands, you had to lick your lips to stop more cum entering your mouth.

"You..." you muttered

"Hmm?"

"You pulled out..." you said.

"Well yeah, I said I would. Remember this afternoon?"

You think back to a few hours earlier, and how she promised to cum outside as long as she could fuck you again. Considering how Gwen was acting, the last thing you expected was restraint. Was there something that witch didn't tell you?

"Yeah... but.."

"What you thought I'd forgotten?" she smirked again "Hoped, even?"

"N-No." You said unconvincingly.

"I dunno... your pussy was trying real hard to keep me in there... Wanna tell me what you were thinking when you came on my cock...?" She rubs her shaft along your slit.

"Shut up.." you mumble as you feel yourself leak fresh juices. You turn your cum-covered face away from her as you lick your lips again.

"Does my cum taste good?" You feel her get off you and suddenly her cock is in your face. "I can always cum inside your upper mouth instead.." she says as she prods the tip against your lips.

You push down the urge to open your mouth and turn over onto your front "Fuck off and untie me, I need to shower."

"Awww, sorry don't be mad, I was only teasing!" she said, half-apologetically. You felt the cuffs click and loosen, and your hands were finally free again. You slowly get up, being ultra careful to keep Gwen's cum away from your crotch, (and hoping she doesn't see how much her teasing turned you on) and make your way into the bathroom.