A Sibling Secret

"I love you bro! I love you so, so -- Mmmm!" Sweat poured down between their rutting bodies and Kit arched and howled as the tightness in her belly twinged and threatened to snap any moment.

"I love you sis!" Thomas cried back, "I've always loved you like this!" His balls slapped her ass in his abandon, and he thrashed her soaking pussy. They both felt his throbbing, her tightening, and knew it was now or never. Kit didn't stop posting when she held her brother's face and stared into those familiar eyes.

"Cum in me."

"Kitty? But you're -"

"Cum in me bro! I love you -- I want you to cum 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 cum Thomas. Oooooh! Give me your baby, bro!"

They came. Kit screamed and thrust down just as Thomas rutted as deep as he could inside her unprotected body. Hot cum erupted deep inside Kit, spraying her belly full of his brotherly seed. He grasped her hips tight and held her still as she screamed and shook, keeping her pussy gripping around the base of his cock as his balls launched all of his load against her inner walls. Kit 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 cum.

By the time Kit had collapsed onto her brother's chest and his cock twitched out the last of his pent-up load inside her, the bed had become soaked with their sweat and cum. Kit gasped for breath, reveling in the afterglow of the best sex she'd ever had, and Thomas did the same. Before long they were kissing again, holding each other as they did.

Eventually Kit rolled off to the side and laid on the bed, still panting from their hot exchange. Thomas laid next to her, staring up at the ceiling.

"Kitty...?"

"Yeah, Thomas?"

"Are you... did you mean it? What you said about..."

Kit thought on it. Risking that with her brother was insane, sinful even. But at the same time... Kit ran her hand over her belly, feeling it slowly lift and drop from her deep breathing. Below her hand she could feel Thomas's sperm, hot and thick, oozing inside her and drooling out over her pussy lips like thick syrup. But so much more was right in there, doing its work inside her sisterly womb.

"Well..." Kit said, still looking at her belly, "...Yes."

"Yes? To what?"

"All of it." Kit 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, Thomas."

"God..." Thomas stared at his sister, mouth agape. Then it curled to a smile.

"I love you Sis."

"I love you too, bro." Kit smiled back just as wide. Cuddling closer though, feeling his cum squishing out between her thighs, she regained her naughty grin from before. "But you know Thomas..." she said.

"W-what? What's wrong?" Thomas asked.

Kit wrapped a leg around his, rubbing her messy pussy against his thigh as she whispered, "You're going to have to give me a lot more cum if we're going to make a baby, dearest brother..."

Four Months Later

And he certainly did, all through the summer. Kit nudged Thomas 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!" Kit huffed. Thomas 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," Kit 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? Thomas 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," Kit grinned, watching Thomas'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?" Thomas 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. Kit giggled.

"That's my little secret, bro," Kit 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," Thomas 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-" Kit 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..." Kit peeled off her pants and smiled devilishly, revealing her lacy thong to Thomas, whose cock was nearly bursting from his pants already.

"Siblings know how to keep a little secret, right?"