First her tight ass, then her tight throat

You pull down Rachel's bikini. Then you spit in her asshole and start sinking in deep. Rachel moans, hardly even trying to hide it anymore.

You thrust in and out of Rachel's asshole, barely building up to a medium pace before Rachel is already quivering around your cock.
"Damn sis, you must've really wanted this," you say to her.
Rachel doesn't respond, too overwhelmed with pleasure to think of a snappy comeback. You're sure she's annoyed in the back of her mind, though.
Then you grab Rachel's throat and really start slamming into her asshole ruthlessly. You fuck her so hard her body bounces up and down involuntarily, and her multiple anal orgasms leave her with a spasming asshole that pleasures your cock nicely.

You **** Rachel out as you fuck her ass for a few minutes. Not too surprisingly at this point, your little sis makes no move to get your hands off her neck. She's actually getting off on the asphyxiation while you brutally piston in and out of her tight fuckhole.
PLAP PLAP PLAP PLAP PLAP PLAP
You fuck Rachel's ass much rougher than you fucked Amy's, who's now watching the two of you and recording it on her phone.
Rachel's asscheeks ripple. She's too lost in the pleasure to notice Amy, let alone open her eyes. Which is why she barely notices when you pull out of her ass and shuffle over to her face, opening her eyes in surprise as you roughly fuck her mouth and make your little sister taste her own ass. Now Rachel finally protests, slapping at your thighs and trying to push you off, but it's too late now. You **** your sister's sweet mouth hard and fast as Amy records and you feel yourself building to an incredible orgasm.

GULK! GULK! GULK! GULK! GULK!
Slowing down your pace, but not your roughness, you pound into Rachel's facepussy. Everytime you bury yourself to the base in her mouth, you savor the feeling of her teen gullet convulsing around your cock. You also enjoy the feeling of your balls slapping on her wet chin.

"Uhhhh~ FUCK Rach, your throat is SO--"
GULK!
"FUCKING--"
GULK!
"AMAZING!"
GULK!
Rachel's entire body jiggles each time you slam yourself to the hilt in her face.

GULP. GULP. GULP. GULP.
Rachel's soft gullet repeatedly tightens around you as she gulps down your precum. Unable to control yourself any longer, you explode down Rachel's swallowing throat for a balls-draining throatpie, her second one today and definitely not her last.
After 30 seconds straight of shooting ropes down Rachel's gullet, you finally pull out.

"Fuck, sis," you pant. "Your throat is the best I've ever had. Seriously, that's an A+ fucking throat."
"Thanks, I guess," Rachel says reluctantly. "I still don't like it though, especially when you make it hurt so bad."
"Aww Rach, but that's the best part!" you say as you pinch her cheek.
She scowls at you silently.
"Well, that was fun," you say. You reach over and slap Rachel's ass. "Thanks, sis."
"Whatever," she says.
Amy blows a kiss and waves her fingers at you as you get up and leave. "Bye, cutieeee!"

You overhear their conversation as you walk away.
"Why'd you say he was cute?"
"Because he is! Like, whaddyou want me to do about that?"
"But he's, like, so gross and horny all the time!"
"Well he's got a nice cock. And it's not like you hated it. I saw you basically cumming your brains out and--"
"Oh my god, shut up! He can still hear you!"
Their conversation dies down to a whisper as you walk away, chuckling to yourself.

*Credit to bryz