She thinks with her D - wow that saying is actually true

As she thought about the night at the sorority and how fucking hot it was seeing her sister being her slutty self in public Emily's cock started to harden again.

She opened her mouth to call Alex over before a thought occurred to her that she had to say aloud. "Am I just going to want to fuck all the time now?"

She was not a prude before this started. Hell she basically had to masturbate every day just to stay sane. At home that wasn't exactly easy, nosy parents and all. She had figured that going to university would mean she have more time and freedom to explore herself, exploring Alex was an incredible bonus. Her cock jumped as she thought about exploring Alex some more.

BUT! she **** herself back on her train of thought. She did not think she was basically addicted to cumming. If she can't stop thinking about fucking for five minutes there is no way in hell she is going to be able to attend classes let alone do any assignments and the marker, while incredibly useful and she had no doubt she and Alex could put their heads together to figure out a way to get around most if not all of university work, and maybe Alex could say something helpful when Emily lets her head off - stop it.

Emily considered a cold shower but had no doubt that was going to end in her fucking her sister as the water cascaded over their bodies.

"Ok Emily time to make a choice." She said it aloud to **** herself to focus on the issue and nothing else. She loves Alex and she loves f- intercourse in many forms. She hoped keeping things clinical could help cool her off. But she doesn't want to be a walking intercourse machine. She went to uni to become a psychologist. When Alex was being bullied in primary school Emily wanted to beat the bully up but her mum said to try talking first. Turned out that bully was having some serious problems at home and by asking about it Emily actually helped them. She loved the idea of talk to people and helping them. Before the Marker that drive was all she thought about. Now she had gotten her dick in her sister that is all she can think about. She could make a living out it but was she just going to throw away her dream to do porn with her sister?

The Marker would make porn success pretty easy. But from what she knew of it's ... machinations seemed the best word, it wasn't going to help with being a psychologist unless her clients let her write all over them. Thinking about it she could probably just tell them it was a part of their therapy. However, that doesn't solve the problem of getting a degree.

She took the Marker out and glared at it trying to think of what she should do. The easy way or the hard way. As she thought she heard the shower shut off. With Alex coming back she wasn't going to have time to think without a slutty sister addling her mind with her fuckable ass and kissable lips. Emily's tongue flicked out to lick her lips at the thought.

She realised that this was just sad. How does she have this little control over her libido? The Marker could solve that.

She popped the lid off and help the tip to her skin before stopping. "Fuck." She said putting the cap back on. If she used the Marker to solve every issue she would never stop and if she finds a problem that can't be solved she'll be fucked. The thought of her ... No enough of that have some fucking will power woman, you are not some sex obsessed guy who only thinks with his dick, you have a pussy and that means you thinking with your fucking brain.

She slammed the Marker down as Alex walked into the room wrapped in a towel deliberately folded to cover her nipples and her pussy only if she stood stock still. So with her sister walking over flashing her pussy with each step Emily held up a hand. "No more sex we need to study we have classes soon."

Alex didn't miss a beat. "Sure thing sis just let me know if you need any relief." She grabbed her laptop and walked to the hallway. "I'll be in the study."

Emily actually felt embarrassed. Her sister who Emily was sure was hornier that she was just causally walked away to study. She also called her room the study so Emily guessed that they were officially sleeping together full time now. Her heart fluttered a little at that but she clenched her fist and took a breath. Study first, bury your cock in your sister/girlfriends pussy/mouth afterwards.

She strode to her/their room and took her laptop back to the living room. Opening it she looked through her emails. There were a lot. Welcome to uni emails with maps and guides; welcome to courses emails from lecturers; emails about the facilities the uni offered, she had a quick skim to remind herself, the gym, cafe, library, apparently the uni even had a bar/night club that was open for students on Fridays, don't think about Alex in a clubbing dress, don't think about Alex in a clubbing dress, don't... Lastly an email Omega Pi Sigma detailing her tasks. She should study so she left it unread and closed her emails instead opening up the uni's website to review her courses and go over the readings.

It was interesting and as she reread the basics she had know since high school she felt that spark coming back that love of both learning and this topic. She loved understanding people, she loved how everyone was different and how everyone could be understood.

"Hey sis you ready to get something to eat?" Alex's voice pulled Emily from a suggested reading about how frames of mind could be broken into categories and from there methods of comprehension changed.

Emily checked the time and saw it was almost 6pm. "Yeah sure." Emily got up and saw Alex smiling at her. "What?"

Alex came over and pecked her on the lips. "It's nice to see you back to yourself. Honestly it was kinda weird seeing you not studying for so long. Even pumping cum into me is the reason for it." Her eyes were dancing as she said the last part and jumped back giggling as Emily tried to wrap her arms around her.

Hearing Alex say that made her feel much better. She was right fucking her sisters brains out was amazing but it wasn't all she was. "Come back here." Emily giggled back. But now study was over and cum stuffing was back.

Alex giggled and ducked around the couch with Emily behind. The two chased each other around the living room, dodging the furniture. It had never occurred to Emily but running around naked with a cock was not as easy as she thought. She was terrified of banging it on something other than Alex so had to move much slower than normal. Something Alex was taking full advantage of deliberately slowing until Emily almost caught her before dashing away.

It was surprising really fun. Play a game like actually sisters was a really good change of pace but the fact Emily hadn't eaten anything where as Alex had gotten a decent protein meal earlier.

Emily slowed down and Alex slowed with her sense the game was coming to an end. "Ok sis what do you want?" She walked into the kitchen leaving Emily breathing a little heavily to sit on the couch. "We have some take out menus..." Alex said bending over to look at the menus on the fridge. When the pair arrived in town their parents suggested grabbing menus from all the local places so they were prepared. She doubted her parents would have ever considered those menus would be used as way for Alex to tease Emily.

"There's Thai." As she said it she lifted a leg a little to spread herself a little wider. "Chinese." She put it down, spreading her legs and making her pussy lips part slightly. "Indian." She took the menu off the fridge and bent lower looking between her legs at Emily with a dirty grin on her face. "Pizza?"

"Sure." Emily said. Her cock had been soft from the running but was hardening right now.

Alex giggled again and took the menus over to Emily. She put her legs on either of Emily's waist and sat down on her lap sandwiching Emily's cock between their bodies. "Let's try this again. We need to order some food becasue neither of us are going to cook tonight. Me becasue cooking it hard when your sister is filling your pussy with her fucking amazing cock over and over and pump her third load of the night inside. And you becuase I have just spent hours studying with no sister cock in me and I am **** to feel you split me open. So, Thai, Chinese, Indian or Pizza?" With each sort offered she tapped the menu onto Emily's cock head.

"Thai." Emily groaned. She was quickly losing the ability hold back.

"Great. I think I'll have the Pad Thai." Alex reached down and gently stroked Emily's cock head as she spoke.

"Me too." Emily said, she did like Pad Thai and going through a menu right now was too much.

"Great I'll make the call." Alex said getting up and grabbing her phone. Emily was glad for the reprieve. They did need dinner and if Alex's teasing went on much long they were going to have gone hungry. "Hi, I'd like to place an order." She looked at Emily and her hard cock pulsing with her heart beat. "Do you deliver? Fantastic." She walked over to Emily and in a smooth motion sat on her sisters lap taking the full length of her futa cock into her pussy. "hhhhh." She muffled into the phone.

Emily rolled her head back to stop from moaning into the phone. After the teasing her hips started the thrust on their own pumping into Alex as she was on the phone.

"Sorry," Alex said, her voice catching with each of Emily's thrust. "Can I get two P-Pad Thai. Fffff." Alex moaned as Emily grabbed her hips to give her thrusting more control. "B-Beef please." She leaned down and kissed Emily's lips before pulling back. "One large," Emily took a hand off her sisters hips and slipped it between them to toy with her clit. "fuc-fired rice, six s-spring rolls and mmmm, sorry and," She pulled away from the phone for a moment to mumble into Emily's ear. "If you don't slow down I'm going to cum on the phone." She brought the phone back to her face and looked at Emily as if to challenge her.

Emily was about to go for it before she realised that making her sister cum on the phone with take out might impact their future take out options. She slowed down a little. Alex looked a little disappointed. "two red curries with chicken." She dropped her hips and landed on Emily, the sound of their hips meeting without doubt being heard by whoever she was talking to. "Amazing." Alex moaned grinning down at Emily. Emily couldn't resist and spanked her sister. "Harder." She mumbled with a wink. "Sorry hotter. Great we are at."

With the ordering done and the phone hung up Emily leaned up and caught her sisters lips. "You are fucking slutty as hell sis."

"We both know you love my sluttiness, you wouldn't be balls deep in you sister if I wasn't a slut." She kissed Emily once. "Also we have half an hour before they get here so either you are to have emptied your balls in my slutty little cunt, and we will be showered and ready to receive food and pay or one of us is going to be talking to a very embarrassed delivery driver."

Emily moaned a little. "Like you don't want to greet the delivery driver butt naked with my cum leaking out of you."

"I'd prefer if you were still fucking me." Alex giggled as the two resumed their humping.

It had only been a few hours since Emily had cum and she was surprised by how long she was lasting. Actually it was kinda surprising she bust a nut into Alex during the phone call.

"I love you so much sis." Alex mumbled leaning forward to lay against Emily resting her head on her big sister's shoulder.

"Love you more." Emily responded moving their bodies apart slightly so she could return her hand to Alex's clit. The moment she did Alex let out a sexy moaning gasp.

"P-Prove it." Emily went to town on Alex's clit as she pounded into her.

Emily was getting close to her limit. "I'm about to babe."

"Babe?" Alex leaned back slightly. Then Emily felt two pairs of fingers start to play with her nipples. "I'm not your babe, I'm your sister. The sister in love with you, the sister addicted to your cock, the sister you have turned into a wanton cum slut. If you call me babe it had better be followed by b sister." Emily groaned as she came, pulling Alex down to make sure she came as deep into as possible. "And the sister you are going to knock up at this rate."

Emily sped up her fingers on Alex's clit and pretty soon Alex joined her in orgasm.

The two stay together for a while cuddling before it occurred to Emily that Alex was right. At this rate Emily was going to pump a kid into her kid sister. Unlike previously this a problem the Marker was going to fix, She has no idea how condoms feel and would find out at some point but the two were going to be raw dogging. They could get Alex on the pill but... Marker. Just a matter of what she should write.

The idea of knocking up her sister should have felt weird, she took a moment to appreciate how hilariously normal that was to her right now, but it was made her feel kinda nice. She loved her sister and having a kid with her did sound kinda, pleasant, like how their life together could go forever. But she didn't want to have a kid right now.

"Wait here." Emily said lifting Alex off her. As she did cum started to leak out of Alex and Emily felt some primal urge to not do what she was about to do and let Alex get knocked up. However she decided to not think with her dick so she didn't have any choice.

She grabbed the Marker, uncapped it and approached Alex, thinking of what to write and the intention behind it. She didn't need to know where to write it because looking at the cum oozing out of her there was only one stop to write.

"Oh whatca gonna write?" Alex asked with interest as Emliy brought the Maker to her smooth mons.

Fertile.

As she wrote she focused her intent. Fertile meant control over fertility, specifically Emily had control over Alex's fertility. She trusted Alex to never take a stupid risk without getting Emily's permission but as she wrote something about having the power to make her sister fertile when she wanted appealed to her. Damn it thinking her dick.

"Um?" Alex asked sounding kinda unsure about what she was reading.

"From now on you can only get pregant," she almost said when Alex wants, misleading her about the effect. "when I want you too."

Alex reach down and for a momet Emily thought she would try and rub out the ink. "Fuck sis that is so hot." her finger moved further to scope some of the cum and lick it off her fingers. She looked up at Emily. "What about you? Want to knock up each and every chick you fuck?"

She made a good point. Emily looked at cock and felt like having a matching mark with her sister sounded kinda romantic. "Ok sis." She offered the Marker to Alex and and held her cock giving Alex access to her mons. "I want to only be futile when I want to be." Alex reach the Marker up before Emily stopped her. She realised that if she was mid fuck and her dick took over her brain she could end up knocking up fucking everyone. "But only if I decided to be fertile before having sex."

Alex leaned forwards and kissed Emily's mons before writing.

Fertile.

"So I take it that means you are going to knock me up sooner of later huh sis?" Alex's teasing tone held a hopefully note and Emily cupped her face and smiled at her.

"Yeah, I, I really like the idea of having a family with you baby sister." Emily winked.

"But sister we already are a family." Alex grinned back and the pair laughed. "Ok I need to shower again so you are going to be getting the delivery." Alex stood and walked to the bathroom swaying her hips as a streak of white ran down her thigh.

Emily sighed and got up to get some clothes on, no point flashing the delivery driver.

The food arrived pretty soon after and Emily paid and arranged the food. The two red curries went into the fridge for a later meal and she started to nom on a spring roll as Alex came out of the bathroom. The pair hugged and got to eat chatting and flirt as they did.

Emily ate all of her food but was so hungry she ate most of the fried rice and one of the curries. She guessed that making all that cum for her sister actually required energy.

After dinner the pair went back to studying.