This is a work of fiction. This is the version with the formatting fixed.
Young sister, older brother
Emma shot Alex, her brother, for the fourth time in a row on the video game they were playing. He sighed.
"How are you so good at this?"
She shot him again. "Because I'm me, I'm perfect."
Those words stayed with Alex.
The word 'perfect' triggered some sort of reminder, and he started looking his little sister up and down. Since he was 13, he remembered feeling sexual attractions for his sister. Now that he was 17, and she was 13, those hormones had caused him to become horny even at the thought of her.
Some days he would peer into her bedroom to watch his little sister playing with her toys or sleeping peacefully. More recently he'd started masturbating over thoughts of her. He wasn't a pedophile, it's just that he'd been with his sister for so long and been attracted to her all his life that he was still frustrated that he couldn't say anything.
Today, he felt that he needed to do something. His parents were out at a meeting and it was late at night. Casually, he dropped in a sentence.
"Do you know what sex is, yet?" he asked.
Emma looked at him, mouth open. "Of course I do! Stop trying to distract me!" She shot him once again.
"Have you ever had sex?" Alex smirked, staring into Emma's blue eyes that were staring at the screen.
"None of your fucking business!"
"Oh, okay, I thought you had. Obviously not."
Emma smacked him playfully on the arm. "Well then you'd be fucking right. I'm only 13, asshole." She gave Alex the tongue, and continued playing.
Alex retreated a little after that statement. She was right, at 13 she shouldn't be in contact with anything sexual. He was about to give up when she said something that shocked him.
"What is that thing you do in bed?"
Emma sighed pitifully. "Don't think I haven't seen you do it. Under the covers... you move your hand up and down. It's like you're playing with your wiener. I've been watching you through your door."
Alex stared at her in shock. So she'd been watching him as he masturbated.
"Huh? Oh, that's something called masturbating... it's something guys and girls can do."
"But we don't have penises!"
Alex pointed as close to her crotch as he could. "You can do it with your vagina. Here, let me show you."
He couldn't believe those words just came out of his mouth, nor could he believe that he was pulling down her pyjama bottoms to reveal a tiny pink vagina. It was moist. Emma didn't struggle as Alex directed her fingers in her slit and moved them about.
Emma shut her eyes and tilted her head back. "Yeah... how did I not know about this before?"
"I quote from Emma about 2 minutes ago: I'm only 13." Alex laughed, watching her masturbating in front of him, trying as hard as he could not to look aroused. He felt the blood rushing into his penis, making him semi hard, but he was sitting with his knees by his shoulders so she couldn't see.
Alex gently moved her hands away and rubbed her himself. This time she moaned. "Oh, that feels good, Alex..." the sound of her voice whilst she was being pleasured was so sexy that Alex could have cummed right there and then. But he wanted to go further than that.
Whilst rubbing her, he stood up and gently pulled his pyjama bottoms down, revealing his semi erect penis. Emma opened her eyes to see the said penis standing horizontally from his body.
"Oh my gosh! Alex!" She began to try and get up.
"Ssh... it's okay, I'm your brother."
Emma calmed immediately, and held her inquisitive gaze at his penis. He looked at her looking at it, and it gave him a full on erection.
"It got bigger!" She smiled at him. "How did you do that?"
"Ah, well I can't control that. It happens when I'm horny."
"You're horny now?"
Alex went slightly red.
"I guess, yeah."
"Well... let me try something I saw once." She leaned back forward, on her knees, and touched his throbbing dick. "Oh my gosh, it's so warm!" She jerked it backwards and forwards at the speed a 13 year old girl would.
Alex was experiencing his younger sister masturbating him voluntarily. He stood there for ages, just letting her masturbate him. He felt close to cumming when suddenly he felt something warm and soft engulf his dick. When he looked down, he saw his cock inside his sister's mouth. After just a few strokes of what felt like heaven, he orgasmed hard. She didn't move her head, though she felt something flying into her mouth. He shot pulse after pulse of thick white cum onto her tongue, and he moaned.
"Emma..." he panted.
She removed the cock from her mouth and opened it to show Alex. He tongue was covered in a thick white layer of his cum. That was his cum in his sister's mouth. Then she swallowed it.
"Emma!" he continued, "There is no way that was your first time..."
Smiling at him, she went to go and suck his penis again as it was becoming flaccid. He moaned as she did so. She sucked out the remaining cum that was still in the shaft before wiping her mouth and giving him a playful wink.
His 13 year old sister had just given him a blowjob.