Marble's sleeping sister

*several days later*

The morning after Marble came inside Maud’s mouth had been totally normal, except for Maud eating a little less breakfast because she said she wasn’t that hungry, besides that nothing had changed so Marble kept her promise not to do anything else to Maud. That is until tonight. Marble had been working harder than normal today so was looking forward to her nightly relaxing shower. While she was taking it though, all she could think of was that nobody had noticed what she had done. She had cum directly into her sister's mouth while she was sleeping and nothing happened, not even Maud had noticed what happened. What would be the harm in trying it again?

After she finished her shower, Marble went to Maud’s room and looked over her nude sister. Her bed was at the perfect height for Marble to do anything she wanted to, standing up next to it. Marble gently placed her cock head on Maud’s mouth to see what she would do. Just like last time Maud latched on to marbles cock head and started licking and sucking. Since she was getting her cock sucked she thought she might as well repay the favor, by rubbing Maud’s soft tits again. She reached out and groped her sister's tits and pulled and played with her nipples. Marble wasn’t on the verge of cumming like last time so she was better able to experience the feeling of her sister's mouth on her cock head. The best part though was when she would move or lick her tongue, it was an explosion of pleasure that rocked through her whole body.

Eventually Marble could feel herself getting close to cumming, why didn’t she want to do this again? There was no worry of getting caught, and her sister's mouth felt so good on her cock. Maybe she would make it a new nightly routine to come visit her sister, instead of just jerking herself off in the shower before bed. As she felt her balls clench up releasing their cum, Marble once again locked up making it so even if she wanted to pull her cock out of her sister's mouth, she couldn’t. Maud once again drank down her sister's cum and sucked her cock dry. Marble wondered why she thought that this was a bad idea a few days ago, this was the best idea she had in a long time.

*a week later*

Every night for the past week Marble had been getting Maud to suck her off, but tonight she had a different plan. She was going to stick her cock in her sister's pussy, not all the way of course. She didn’t want to fully take her virginity or anything, she just wanted to know what a mares’ pussy felt like. After her shower Marble went to Maud’s room; even though she’d already decided she was going to do this, it didn’t mean she wasn’t scared, or nervous. Sure, she had tongue fucked her sister till she came, but this was still a new experience.

Here she was, kneeling on the floor staring at her sister's slit wondering what she should do first. Marble gathered her courage, took a deep breath and leaned forward. Like the last time she had done this she started first tracing the outline of the pussy with her tongue, almost immediately she could feel moisture starting to seep out of her sister's pussy. She decided that first she would get it ready, her cock wasn’t small, and her sister was still a virgin. She pushed her tongue in as deep as it would go, tasting the sweet nectar hidden within. Marbles tongue swirled and prodded with both pleasure, and impatience. Once she was sure the inside was well lubricated, and tasted she pulled her tongue out and started to use her fingers to spread Maud’s tight virgin pussy. Marble plunged her middle and index fingers in and started wiggling them around inside, trying to stretch her insides in different directions. After a while of working her sister's pussy she pulled her drenched fingers out and stood up, this was what she had been waiting for.

Marble rolled Maud on her side so that she was facing towards the edge she was on, and to give her easier access to Maud’s pussy. She grabbed her 15 inch long member and pressed the head up against Maud’s pussy lips, then very gently she started pushing forward. The sensation of just starting to push in was amazing, Maud’s pussy was hot as a furnace, and tight as rubber. Marble had to gently thrust back and forth for a while before her flare finally popped inside. Only the first inch or so of her cock was in but the heat and tightness was amazing, it was like Maud’s mouth, but better in every possible way. Marble slowly thrust her tip in and out, making sure not to hurt Maud’s hymen. After a few thrusts Marble had a sudden realization, she had no idea what she was going to do if she came. She quickly pulled herself out and stuck the head in her sister's mouth, thankfully Maud latched on right when she started cumming, and drank her cum down like she did every night.

While Maud finished milking her cock of her cum, Marble started to think about what she could do to deal with the cum problem. She couldn’t just cum inside her sister she might get pregnant! Unless… she wouldn’t have a chance of pregnancy if Marble only came inside when Maud was on her safe days. That was the answer! She would find out when Maud was safe and if she just played with her pussy then, she would be totally fine to just cum inside. Just thinking about the idea of cumming inside Maud made Marbles cock deliver another blast of cum to Maud’s still sucking mouth. Marble could feel what it was like to cum inside a mare. All she had to do was find out when Maud’s safe days started next.

*A few days later*

Marble was lucky she pulled out the night she did, Maud was still fertile then but it was only a few days till Maud’s next safe cycle started. Marble knew for sure that tonight there was no chance that Maud could get pregnant, and she was ready to finally cum inside her. It was especially exciting because since that night Marble had been putting her dick in Maud every night to keep her nice and stretched, and it was even more pleasurable than just having her cock sucked. Tonight, though she wouldn’t have to pull out and just cum in her mouth, tonight she could cum inside. It was getting more exciting to see Maud every day, she had no clue what Marble was doing to her every night. Or what she thought about doing to her during the day.

Here she was standing above her sister again, dick rock hard, balls full of cum, ready to “breed” a mare. As soon as Marble touched Maud’s pussy she felt it was wet, it seemed like her body followed its cycles, it knew when to go to bed, when to wake up, and when to get wet for a horny futa to fuck it. Marble wasted no time turning Maud over so she could reach her pussy. She grabbed her long hard cock and started pushing it in, stopping when she felt that barrier that represented her “virginity” through that barrier had been taking a beating over the past few days from a certain anxious futa. Once she was in as far as she could go Marble started rocking her cock back and forth inside her sister, she could feel it clenching and caressing her cock head the entire time. She started to move faster and faster, losing her composure at thoughts of being able to cum inside. Eventually she felt the telltale sign of her balls churning getting ready to cum, and she kept thrusting. When Marble came she didn’t just lose her own virginity from cumming in a mare, but also blasted through what was left of her sisters abused hymen, sending her cum deep inside Maud.

*a few days later*

Either Marble didn’t notice, or didn’t care that every night after her cock would fuck deeper and deeper into Maud’s pussy. Tonight she had gotten 8 inches inside Maud’s pussy, more than half her length was now plunging into her sister every night before she pumped her cum deep inside. She hadn’t cum yet tonight though, as her thick pole slammed into her sleeping sister, Marbles hips thrust back and forth at a rapid pace. Nights of slow fucking, scared of waking or tearing her virginity were long gone now. Marble knew that she was fucking Maud and planting herself deep in her every night, and she loved it. The pleasure she was getting right now fucking a mare, especially one as beautiful as Maud, was like a drug. She only hoped that she would be able to fit her entire cock inside Maud before too long.

*days later*

Marble was excited for tonight, Maud had just gone through a set of danger days and she could finally Fuck Maud again, right before the danger days hit she had almost hilted inside her. Maud’s pussy was drenched and waiting like it was almost every night these days, all marble had to do was roll Maud over and she could start plowing into her. Marble rolled Maud away from her and pushed her cock against Maud’s entrance. Marble knew tonight was the night that she would finally hilt all the way inside Maud and fill her deepest parts with her cum. She started pushing herself in her sister, feeling every inch of her cock entering Maud’s tight pussy. Suddenly Marble hit a wall, literally. This wasn’t just the tightness of an un fucked bit of pussy, this was her cervix, Marble could go no further and she still had an inch outside of her sister. She knew her dream of hitting her sister had now been shattered, but that was just a side thing to do, the main thing was still fucking her sister.

Marble pulled her thick futa cock almost all the way out of Maud, her tip barely still inside, then she slammed herself all the way into Maud. Marble kept fucking her like this for a while, slow long hard thrusts that would drive any mare to her knees begging to be foaled by Marbles thick virile cock. Marble kept thrusting like this for many long minutes, unknowingly doing the same to Maud’s cervix as she had with her earlier hymen, fucking it into submission. Marbles thick head battered against Maud’s cervix again and again like a battering ram trying to breach a city. Marble is still standing behind her sister as her cock jackhammers in, panting and thrusting her cock as deep as it can go. Then just as she feels cum shooting up her cock she feels herself hilt all the way inside her sister.

Marbles cock finally fucked its way past Maud’s cervix and entered Maud’s womb, the head expanded locking Marble in to Maud as her cum coated her womb. If this wasn’t a safe day Maud would be guaranteed to be pregnant. Thick futa cum first coated then filled her womb to capacity, Marbles dick was doing what it was made to do, ensure a mare is bred as much as possible. It took a while for Marbles flare to shrink enough to let her pull it out of Maud’s womb, and when she did a small river of cum followed it out. Marble was amazed that she had managed to pierce Maud’s womb, but she couldn’t deny that fucking a mare to the womb was the best thing she had felt yet. Marble was determined to fuck Maud’s womb every night after this, if it’s a safe day only… right?