"Me too - Fuck! Sis, I'm gonna c*m too."
Tara's heart pounded. Her nerves thundered. Her p*ssy quaked. She felt her brother's c*ck, his beautiful c*ck, jabbing deep inside her, sheathing inside her so perfectly, so completely. She'd always loved her brother, from the moment he was born she loved him. But now her love grew beyond what she ever imagined it could be. She loved her brother like a sister shouldn't. Like she always wanted to, deep down.
"I love you bro! I love you so, so -- Mmmm!" Sweat poured down between their rutting bodies and Tara arched and howled as the tightness in her belly twinged and threatened to snap any moment.
"I love you sis!" William cried back, "I've always loved you like this!" His balls slapped her a*s in his abandon, and he thrashed her soaking p*ssy. They both felt his throbbing, her tightening, and knew it was now or never. Tara didn't stop posting when she held her brother's face and stared into those familiar eyes.
"C*m in me."
"Kitty? But you're -"
"C*m in me bro! I love you -- I want you to c*m in me!"
"I can't, ragh! -- I can't hold back sis! What if I get you-"
"You will! Ahhh! God you will! Yes!! Give me your c*m William. Oooooh! Give me your baby, bro!"
They came. Tara screamed and thrust down just as William rutted as deep as he could inside her unprotected body. Hot c*m erupted deep inside Tara, spraying her belly full of his brotherly seed. He grasped her hips tight and held her still as she screamed and shook, keeping her p*ssy gripping around the base of his c*ck as his balls launched all of his load against her inner walls. Tara felt his potent sperm splash against her cervix and wailed, another wave of her climax washing over her just from knowing her little brother was filling her womb with his c*m.
By the time Tara had collapsed onto her brother's chest and his c*ck twitched out the last of his pent-up load inside her, the bed had become soaked with their sweat and c*m. Tara gasped for breath, reveling in the afterglow of the best sex she'd ever had, and William did the same. Before long they were kissing again, holding each other as they did.
Eventually Tara rolled off to the side and laid on the bed, still panting from their hot exchange. William laid next to her, staring up at the ceiling.
"Kitty...?"
"Yeah, William?"
"Are you... did you mean it? What you said about..."
Tara thought on it. Risking that with her brother was insane, sinful even. But at the same time... Tara ran her hand over her belly, feeling it slowly lift and drop from her deep breathing. Below her hand she could feel William's sperm, hot and thick, oozing inside her and drooling out over her p*ssy lips like thick syrup. But so much more was right in there, doing its work inside her sisterly womb.
"Well..." Tara said, still looking at her belly, "...Yes."
"Yes? To what?"
"All of it." Tara rolled her head to the side and met her brother's gaze, "I love my little brother, more now than I knew possible. And..." she stroked her flat belly, "I would have your baby in a heartbeat, William."
"God..." William stared at his sister, mouth agape. Then it curled to a smile.
"I love you Sis."
"I love you too, bro." Tara smiled back just as wide. Cuddling closer though, feeling his c*m squishing out between her thighs, she regained her naughty grin from before. "But you know William..." she said.
"W-what? What's wrong?" William asked.
Tara wrapped a leg around his, rubbing her messy p*ssy against his thigh as she whispered, "You're going to have to give me a lot more c*m if we're going to make a baby, dearest brother..."
Five Months Later
And he certainly did, all through the summer. Tara nudged William gently, trying to keep quiet as their parents slept upstairs. Slowly his eyes opened, and he looked up hazily at his sister.
"Kitty? Oh hey, you're back already..."
"Already? I've been out all day!" Tara huffed. William rubbed his eyes and sat up, though he kept his hand where it was. He was looking there intently.
"So... what did they say?"
"Oh, the usual. Eat right, exercise, brush my teeth. But then I had to take off my shirt and... well..."
"Well?"
"Well, they found this," Tara stood up and lifted her loose shirt. There, amid her toned and slim midsection, was the slightest curve just below her navel. A little bump even? William touched her gently, running his hand over his sister's belly while looking up at her.
"And? What did they say? Are you...?"
"They said she'll look just like her Daddy," Tara grinned, watching William's eyes light up and his hand pet over his baby nestled inside her belly, "At least, that's what I bet they'll say when they find out."
"Awww, what?" William scowled, "What do you mean? Are you pregnant or not?" He was staring at his sister's tummy the whole time, as if asking it for the answers. Tara giggled.
"That's my little secret, bro," Tara said, smirking down at her frowning brother, "Pfft, you'll find out soon, one way or another. You have been fucking me without a condom every night when Mom and Dad went to bed, you know."
"Sometimes more than that," William reminded. His palm circled that spot, right below my navel.
"Oh yeah... Well, I'm saying don't worry -- we'll be off to college next week, and you'll be moving in with me."
"But wasn't I going to move in with-" Tara gave him a look that cut his words off mid-stream. She arched her eyebrow and rubbed her belly to give some added emphasis.
"Nope -- you're sticking with me, brother dear," she said sternly, but her eyes betrayed her severity. "I'll have to make sure my younger brother does well in college while he's trying to knock his sister up, don't I? And besides..." Tara peeled off her pants and smiled devilishly, revealing her lacy thong to William, whose c*ck was nearly bursting from his pants already.
"Siblings know how to keep a little secret, right?"