You really want to, but you don't have time.

You feel lust burning in your chest... and groin, obviously. It's very easy to forget that she's your half-sister. She's a foxy little piece of ass, who needs to be fucked hard in the ass, held down and choked, who needs her ass reddened with a belt...
You seize a handful of her hair, suddenly. She shrieks in surprise as you pull her over your lap, holding her head down over the armrest by her hair as you roughly uncover her ass cheeks.
"You're a lucky girl, Zo." You have her shorts around her knees, and her wiggling ass is before you, **** and pale. You rear back, bringing your palm down hard against the expanse of luscious ass-flesh. "Lucky that I'm in a hurry."
"Ah!!" she grunts in pain as you bring your palm down again and again, roughly in the same place, until her skin starts to redden.
"If I had the time, I'd show you what happens when little sluts like you cross me." You smack hard once more, this time lingering afterward to slip a finger into her snatch from behind. Sure enough, it's slick with girl cum. "You filthy little whore. You're getting off on being punished by your big brother..."
"Yes...I need it. Give it to me like you gave it to Jenna..."
"No. Bitch, you don't get what you want by just demanding it!" You pull her head up roughly, forcing her back onto her knees. Tears are leaking from her eyes. "You have to earn rewards...." You glance down at the rising tent that had been jabbing her in the stomach moments earlier. "Well? Be quick about it, I don't have a lot of time."

She nods, pulling at your zipper until your cock springs up. Without hesitation, she starts to suck, slurping and spitting as she works the head and shaft with lips and tongue.
"Ugh... come on, Zoe.." You put two hands on the back of her head, pushing her down as you thrust upward. "Put some effort into it."
"Nnnnnnnnnnnn!!!!!!!!!!" She moans in alarm as your dick buries itself in her throat. Your hands keep her locked, balls deep, against you, and she flails a little as you work to **** her throat with your cock.
"Yeah...that's good. Better make me cum fast, I'm on a schedule, here, Zo."
"MM! MM! MM!!" Her deep throated wails vibrate against your cock. She's fighting you, trying to rise off your cock, but your hands keep her down as she gags a wave of spit onto your cock.
"A little longer, Zoe... I'm almost there..." you revel in the absolute power and depravity of it, using her throat as hard as you like. Her wails are turning to moans. You let her up, and she gasps for air; her face is a mess of spit, tears, and precum.
"Take a deep breath, because you aren't done yet..." You grip her cheeks with a cruel hand, digging in with your fingertips to shape her mouth into an "o". "Are you going to be a good little whore and make your big, strong brother cum in your mouth?"
She locks her eyes with yours, and that's when you know... you own her ass. She nods, and falls back onto your cock, this time doing all her own **** by herself, deepthroating and licking the balls as she goes all the way down, gagging and slurping and humming until you can't hold back anymore, depositing a salty snack deep in the back of her throat. She gags and swallows, coughing as you toss her onto her back.
"Holy shit... Jimmy...." she lays on her back, panting, as you wipe your cock with one of her discarded shirts.
"Maybe next time... don't poke a sleeping bear." You toss the shirt at her.
"That was incredible... so kinky..." she's rubbing her throat. It's probably sore: her voice is hoarse.
"I'll see you later." You pull on your shorts and head towards the stairs. "Make sure the plumber gets out ok?"
"That's it? You're not... you're not going to...?" she looks at you with a look of despondency.
"I've got to go, Zoe." You pause, looking at her pouting face. "...maybe next time."
She smiles as you head upstairs to grab your clubs and put them in the trunk of the Javelin. You head out to the club, shaking with adrenaline at what you've done.