Dax was shaking as he replied back to her, "Yes...I am too."  

"Do you have your cock in your hand right now, stroking it?" Beth wrote.

"Yes..."

"Are you thinking about me, and what you've seen today?"

"I am."

"Keep stroking your cock for me then, and do it knowing I'm playing with my pussy right now"

Beth, her mind being controlled by her obsession to see his cock, clicked on the "invite to video chat" icon. 

Instantly, the invitation appeared on Dax's screen.  Still shaking, he hit "accept".  As soon as her pussy appeared on his screen he got harder and bigger than he had ever been before.  He watched, transfixed, as she ran her finger up and down her slit.  She then took her finger and began to rub it in a circular motion near the top -this was her "clit," right?- and he could hear her begin to moan.

From her end, her wet pussy began to drip when she saw just how huge his cock really was.  Not only was it huge, but it had a perfect slight curve to it and she couldn't help but wet her lips at the thought of trying to fit it in her mouth.  Her brother or not, it was by far the best-looking cock she'd seen, even in porn.

"Keep stroking your cock for me, I'm going to cum soon but I want you to cum first.  Jerk it hard for me and cum on your stomach," she said to him over their video chat.

He did just as told and began to jerk off faster and faster, all the while staring at his sister's -clearly trimmed- pussy.  He felt himself beginning to cum so he squeezed himself as hard as he could and aimed his shot towards his stomach.  He was so excited though, that instead of hitting his stomach, it shot all the way up and hit his face and neck.  

Slightly embarrassed, he reached forward to shut off the chat just as her body began to shake... she was cumming then as well.  He watched for another second before clicking off and then leaned back, his mind now filled with the feeling of shame.  He'd have to stay in his room all of tomorrow, there's no way he could face her... maybe ever again!

Beth's mind briefly felt shame just as Dax' was, but a much stronger urge inside of her began to take seed.  She still didn't want to fuck her brother, but a growing part of her was already disappointed that she had only seen his cock on the screen.  She still needed to see it in person...

The next day she began to wonder if he was even home, as she didn't hear a peep from him all day.  She had spent half the day at the pool; no signs of him at his window; and most of the rest of the day lounging around reading.  She figured she should give him a little space, so she did just that.  

They had both received a group text earlier in the day saying her parents were going to stay an extra night, so she knew she'd have a little extra time.  She could wait until tomorrow to start back on her mission.  As it began to get dark, she took a shower and then headed off to bed early. She tossed on her new nightie, no panties, and then decided to open up a window to feel the cool night breeze on her bare skin. 

He, on the other hand, spent most of the day trying to keep his mind off what happened yesterday.  Playing video games, working on his essays, lifting some weights, whatever he could do to distract himself. However, despite his shame, he was still as horny as ever. It was all just too sexy, it overrode anything else he was feeling.  The more she teased him, the more pent up he was getting.  Pretty soon he was going to explode. Pretty soon if she didn't watch out, he might just pull out his cock and fuck her.  

Who was he kidding, he hadn't fucked anybody yet.  Shit, her pussy last night was the first "live" pussy he had seen and even that was from behind a screen.  But he was done being teased by her, it wasn't fair.  His horniness began to gain a dash of anger, and he got up and headed over to her room, intent on giving her a piece of his mind.

When he reached her door it was left slightly ajar, so he opened it without knocking and what he saw stopped him dead in his tracks.  There she was; seemingly asleep; laying on her stomach, one leg stretched out and the other pulled up close to her body.  She was in a white nightie and wearing nothing else, her ass as bare as could be.  

Without any hope of controlling it, his cock started to grow.  He quietly walked over to her and stood a few feet from beside the bed, never taking his eyes off her ass.  Now completely hard, he slowly reached into his shorts and rubbed himself.  She had left on her reading lamp so there was plenty of light shining on her, and from where he stood he could see both her asshole and the beginning of her pussy.  He thought about how wet she had been last night, and his cock began to ache for more.

Trying to be as quiet as possible, he slowly pulled his dick out and took another step closer to her as he began to stroke himself.  His cock was now only a foot or so from her ass, and as he began to jerk himself harder she stirred.  Unsure if she was waking up or not he paused for a moment, only resuming when she didn't move.  As she stirred she had moved, and now she was laying on her side, facing away from him.  That meant her ass was now facing him.

He swallowed hard, and then shuffled forward until his cock was only inches from her.  All he had to do was lean forward and his tip would be touching her.  After a moment of consideration, he did just that.  He grabbed himself, and traced the contour of her ass with his tip.  He ran it along her side, then up near the top of her crack, then he followed it down past her hole and finally found her pussy.  He slowed down and ran himself along her slit... she didn't stir, so he did it again.  This time, she flinched.

He took a step back and she began to stretch, and as she did so she rolled over and was now on her back, her legs spread.  He looked down at her whole body, her nipples showing through the lace top to the nightie, and her trimmed pussy now fully exposing itself to him.  Part of him wanted to turn around and sneak out, but a bigger part of him wanted to grab his cock and shove it inside of her.  He took his dick in his hand and aimed it for her pussy, and then slowly leaned forward again.

His tip pressed against her lips, and as he began to run it along her slit again she opened her eyes.  He jumped back a step, completely caught off guard.  But, instead of yelling at him, she silently grabbed his cock and pulled it toward her.  With his tip against her, she began to jerk his huge dick, not even being able to wrap her hand around it.  

She then took him and ran him along her slit, and to his delight, he noticed she was now wet.

"You can put your tip inside me... but no further," she said to him as she looked him in the eye.

He nodded, and she took her legs, wrapped them around his hips, and then slowly pulled him into her.  It was a tight fit, but her eager cunt took his tip with very little trouble.  At the feeling of her tight wetness, he began to cum immediately.  He pulled back and shot his cum all across her pussy.  Mortified, he turned and ran back into his room.  There was already a message waiting for him on his computer.

"It's ok, shit happens... don't let it bother you.  Maybe we can try something again tomorrow?"

Was she serious?  She wanted to try this again?  He barely slept a wink that night, alternating between shame, embarrassment, and wondering if she really wanted to try again or if she was just being nice.