Go find Melanie

Having satisfied your horniness for Rachel, you go downstairs and look for your big sister, who should be a lot more receptive to your advances. It doesn't take long for you to find her in the kitchen, where she's setting down a big bowl of oatmeal.

You look her up and down. Melanie's wearing a thin, oversized shirt that goes down to her thighs. Knowing her, she's probably not wearing panties underneath, and she's definitely not wearing a bra because her hard nipples are poking through her thin shirt.

"Morning, bro," Melanie says. "Want some breakfast?"
How nice of her. "Sure, thanks Mel."
"Yeah I gotchu." She pours another bowl of oats with milk and puts it in the microwave. "How was your morning? Sounds like you and Rachel already had fun without me." She grins at you cockily, her hand on her hip.
You put your hands up. "You caught me."
Melanie laughs and pulls the oatmeal out of the microwave before garnishing it with brown sugar. "I don't blame you. The way Rachel shakes her bratty ass around the house like she's not asking for it? Shit, I'd do the same if I was born with a cock."

You two eat for a while, catching up. Melanie tells you a bit about college and life at home, and also how your step-mom had already left for work.
"So it's just us three at home the whole day today," Melanie says. You look up at her, getting hard as she says that. Melanie looks at you and reads your face like a book (you're ogling her tits).
"What? Do you need to use me right now?"
"Could I?"
"Yeah sure, no problem," Melanie replies, walking over to you and sitting down on your cock. She eats her banana as she slides her pussy up and down your cock, which is still pretty wet from using Rachel.

"Oh, uhhh. Actually I already fucked Rachel's pussy, can I get your ass?"
"Oh my bad." Melanie repositions and winces a little bit as she slides her asshole down your cock, all the way to the base.
"Fuck you're really tight, Mel."
"Thanks," Melanie says nonchalantly. She bounces up and down in your lap. You reach around her and eat your oatmeal as she fucks you.
You reach up her shirt and grope her fat tits, which you really appreciate since Rachel is so petite and doesn't really have big tits. Melanie doesn't really respond because she's also eating. It's just a casual breakfast assfuck for both of you.

Just then, Rachel walks into the kitchen and sees Melanie casually bouncing up and down on your cock. "Ugh bro you're such a perv! You can't even keep it in your pants for ten seconds, god!"
Melanie responds maturely to her younger sister. "Rach, stop being annoying. David has needs and it's not like those just go away."
"Well, I wish they would go away. He already fucked me a bunch of times since he got back home, and it hurt everytime."
You shrug your shoulders. "Not my problem, Rach. Get better at taking dick."
"What he said," Melanie agrees.
"Fine whatever, just leave me alone," Rachel says in typical teenage annoyance.

Rachel sits down and eats as Mel bounces in your lap. Rachel puts in her earbuds to ignore you two.
After a couple of minutes, Mel's asshole milking you is just too good, and you tell Mel that you wanna cum inside her. Hearing this, Rachel pulls out an earbud and says,"You're gonna cum, David? Can I... have it?"
Mel laughs. "Wow, look who wants David's cum now."
"Shut up, you big meanie," Rachel snaps back. "I just want it on my cereal for more flavor. And it would go to waste in Mel's ass anyways, I'm just being practical. It's not like I'm asking David to fuck me." She crosses her arms across her chest in defiance.

"Yeah? And what do I get for it Rach?" you ask her.
"Ugh. I'm only doing this 'cus I wanna eat your cum right now, but... I guess I'll let you fuck my throat later."
"That's the spirit, sis! Not that it really matters, 'cus I'm definitely gonna fuck your throat either way."
Rachel rolls her eyes. "You're so annoying."

Melanie gets off of you and you walk over to Rachel, and you jerk off into her Cinnamon Toast Crunch. Rachel plays with your balls a little bit as you blow a massive load into her cereal.
"Thanks, I guess," Rachel mumbles under her breath, trying to stay mad at you.

You sit back down and the three of you eat breakfast like a big happy family. You watch Rachel spoon cum-covered cereal into her mouth as she watches Minecraft gameplay on her phone.