Part of me knew it was wrong, but then again, I really had to know.
 
If only to make sure I knew how my sperm affected women. If it affected them at all. I had Tammy and Nichole « collect » my sperm for a while, which never failed to make them pout adorably when they watched my cum fill a glass instead of their mouths.
 
Or pussies…
 
Or Ass…
 
But they didn’t protest and did as I asked like the good little slaves they had become.

Although I spent a lot of time at the girl’s place, I still technically lived with my foster parents.

 

Although I spent a lot of time at the girl’s place, I still technically lived with my foster parents. A part that my cock flexed every time I saw Mindy, the main reason I decided to test my sperm on her was the fact I could have easy access to her over a long period. I started to mix my cum with Mindy’s meals. Easy enough. She never cooked for herself.

I gave her a least one dose each day, sometimes 2 if it worked out good. After about 2 weeks of semi-daily doses, I decided to increase the concentration of “cum per bite” by making her « special milkshakes ». I hoped that what Nichole and Tammy had told about my spunk tasting extra good was true. The first one I made her, she flat out refused.
 
I decided to wait for a hot day and tried again. Success!
 
She took it out of my hands while mumbling a thank you that managed to sound grateful and annoyed all at once. She took a few sips and smiled. Seems the taste was good. Mindy had always been mean to me. I was older than her, which pissed her off. I wasn’t really a part of the family and it made her view me as a free loader, not a brother.
 
After she had a taste, she didn’t refuse when I brought her another 2 days later. Or when I tried my luck the very next day for a third dose. In fact, she was even eager to get another. She even started to act nicer around me!
 
I soon realized that she acted nice mainly to be able to manipulate me into making her a milkshake, nut I didn’t care. I knew it wasn’t something my cum was changing in her, but it made it easier for me to dose her. After about 2 weeks, she offhandedly asked why mine were so good; I simply said it was a secret. Which made her mad.
 
It took a month, but I watched her change. Little by little, I noticed that the annoyed looks she always gave me disappeared. Instead of rush in the bathroom in the morning and taking as long as she possibly could to get ready, she waited for me to go first. Instead of rudely asking me to pass her the salt at dinner, she would ask if I wanted some. It was the little things, but it had a huge impact.
 
I even tried to ask for things. At first, she seemed to resist and find excuses, but after a month, she would smile and do what ever I happened to ask of her. It was nothing sexual of course. But when she agreed to do my chores without even telling me that I owe her, I decided to try my luck.
 
I came into the house and found her in her room talking on the phone with one of her friends. She was wearing a teddy and not much else. I stood in her doorway until she noticed me. She finally did and looked at me, annoyed…
 
« What? Did you need something? »
 
« Nah, just admiring the view. »
 
She placed her phone back on her ear.
 
« Sorry about that, just my idiot brother oogling…. Yeah right? How creepy can you get? »
 
« Hang up. » I simply stated.
 
« Hold on… » she said into the phone. « What did you say? » She asked me. « I’ll call you back Shelly, bye! » she finally said and hung up.
 
Test one, ok.
 
« What is it? WHAT do you want? »
 
« I want to show you something, come with me. »
 
« Really? HHHuuuuu…. What a pain…. » she said while getting up.
 
She complained a little, but as I looked back to make sure she was following, I could see the traces of a smile. I knew my shakes were having some sort of effect because not too long ago, she would have told me to fuck off. Instead, she followed me to the kitchen.
 
Once in the kitchen I went to grab the milkshake I had prepared for her. This one had only my spunk in it thought and almost nothing else. Just enough stuff to make it drinkable.
 
« Here, I made an extra special batch and wanted your input to see if it was better or worst. »
 
She went from annoyed to happy in a split second. She took the drink and sucked in a mouthful. I could tell she tasted the difference. She looked up and the joy on her face almost made me forget all those times she had bean mean to me. Almost…
 
“Oh my gawd !!! It’s even better! You HAVE to tell me what your secret is!”
 
“You want to know what the secret ingredient is.” I said, phrasing it more as a statement then a question.
 
“Oh I do!” she said as she took another sip.
 
“You need to know.” Again… Intoning the phrase as a statement.
 
“Yes…”
 
“Ok then…” I said as I reached in my pocket.
 
I took out the bottle I had filled with my spunk. I uncorked the vial and took her hand. I poured a little in her palm and watched. She sniffed it and looked puzzled.
 
“This is…. You little shit…” she said, suddenly angry again. “Stop fucking around! The jokes over, this is not the special ingredient.”
 
“Oh? Why isn’t it?”
 
“It’s your spunk you pervert!”
 
“Yes, and it’s the special ingredient.”
 
“WHAT?”
 
“Sure, lick it.” I stated.
 
She looked defiant for a moment before putting her tongue out and tasting it. The look of surprise on her face was delicious.
 
“No… This can’t be… This isn’t your sperm…”
 
“It is…”
 
“You have been feeding me your SPERM????”
 
“Yep!”
 
“You sick pervert!” she said as she put the milkshake down.
 
“Don’t lie, you like it.”
 
“I… I don’t know why it tastes good, but it’s still sick!”
 
“Yeah I guess… But it has a very fun effect on women who drink it for long periods of time.”
 
“What the hell are you talking about? Jokes over, I’m going to bed.”
 
“No you are not.”
 
She had turned to leave, but she stopped in her tracks. She turned and looked at me. A little surprised at my tone.
 
“What?” she said dangerously.
 
“Seems Mom and Dad will be out for a little while, why don’t we have some fun?”
 
“What do you mean? What’s going on?”
 
“Remove your teddy.” I stated.
 
She smirked and moved to leave again, but found that her hands were grabbing the bottom of her teddy and pulling it up over her head. The surprise on her face as she realized she had done what I asked was starting to have an effect inside my pants.
 
She wasn’t wearing a bra, which gave me a perfect view of her C cup breasts. They were very nice and perky… Her hands moved to cover herself up as she threw the teddy on the floor.
 
“WHAT THE FUCK!”
 
“Calm down…”
 
“Why did I just do that?”
 
“Because I wanted you too.”
 
“What do you mean?”
 
“I mean… You are mine now… By drinking so much of my spunk, I’ve effectively claimed you. You see, I found out that my sperm has a very special quality, not only does it taste wonderful, as you know, it slowly enslaves the women who drink it. Claiming them.”
 
“Claiming them? What the fuck? That’s insane!”
 
“It is! I didn’t believe it at first, but I assure you, I tested it and... It really does claim women.”
 
She looked at me with fear and confusion. My guess is that she was trying to wrap her head around the concept.
 
“Let’s see if you drank enough of my ‘milkshakes’ to render you completely enslaved…” I said as I advanced towards her.
 
She backed up until she hit the wall, still holding her tits.
 
“Remove your hands from your tits.”
 
“NO!!!! Stop this!” She said.
 
I could see her resisting my order. Maybe she needed more doses before I went this far, but I couldn’t turn back. She fought it as hard as she could, making her hands tremble with the effort. But she eventually dropped her hands to her sides. She looked at them and then at me. More fear than confusion...
 
“Good… Now let’s see if you are a real blonde… Take off your shorts and panties.”
 
“Stop this! Please! We are brother and sister!” She begged as her treacherous hands started to peel down her shorts.
 
“Actually, we aren’t, and you know it…”  I said. “Nothing biological is preventing us from enjoying ourselves. Besides… You always made sure I understood I wasn’t really your brother.”
 
Her shorts hit the floor and her hands grabbed her panties. They stopped as I saw her fight her compulsion to obey me. She was shaking with the effort! It only served to give me a throbbing erection. She finally couldn’t resist it anymore and down went the underwear.
 
I knew it… She was a natural blonde! I could barely see it thought, she kept trimmed and short. I wasn’t a big fan of the ‘bush’, so I thought I would push things along.
 
“Starting tonight, you are to keep clean shaven everywhere.” I said.
 
“Please stop this…”
 
“Oh stop your whining…” I said as I approached her and grabbed both her tits.
 
They were really nice…
 
She whimpered as I molested her boobs. Well, this test was going well for the moment, let’s see if we can go a little further.
 
“Ok Mindy, let’s give you a dose fresh from the source…” I said cryptically.
 
“What… What do you mean?” she asked confused.
 
“I want you to give me a blowjob and drink my spunk.”
 
“WHAT!!! NO!!!! I can’t! You can’t! Stop this! You’re my brother!!!”
 
“Like I said, I’m not... I have this erection you see…” I said as I pulled my cock out.
 
She looked down at it and blanched a little.
 
“Now… Mindy, suck my cock as best you can to maximize my pleasure. Once I cum in your mouth, you will taste my seed and swallow it.”
 
“Noo…. Please… Don’t… We can’t do this…” she protested weakly.
 
I moved back to give her some room. I bumped into the table and had a thought. I jumped up on the table and sat on the edge. Mindy looked at my erection with trepidation as she slowly approached. I could clearly see her inner struggle, she REALLY didn’t want to do this!
 
Each step she took to get to me was a struggle. As if she put her whole will to resist behind every one of them. Once she reached me I could hear her mumbling.
 
“This can’t be happening... This can’t be happening...” she said under her breath.
 
I watched her struggled as she arrived between my legs. She starter to bend down, but straitened up again. Her whole body shivered. For a moment, I thought I had finally found her limit.
 
But she finally caved and bent down. I watched her blond hair reached my cock and I felt her tongue lick the tip of my shaft.
 
“Tell me Mindy, have you ever given head before?” I asked as I caressed her head.
 
“I can’t tell you... that...” (Lick)
 
“You will always answer me with the truth.” I said.
 
“I... No...” (Lick) “I... Yes... I have...”
 
“Oh? Damn... Just one guy?”
 
(Lick) “Bastard... Y... No...” (Lick) “3 guys...”
 
“WOW Mindy... Did you put out with any of them?”
 
(Lick) “Only... 2 of them...” (Suck)
 
I let her continue for a little while, watching her head bob up and down between my legs. She wasn’t bad. Of course, after almost a year of refining Tammy and Nichole’s technique, Mindy wasn’t near their talents, but her technique did bring new sensations and I loved it.
 
“Well I can tell you this much... You are pretty good at that...”
 
She just made a scuffing sound with my cock in her mouth, indicating she found the idea laughable. Maybe absurd... Maybe she thought that her brother complimenting her sister on her blowjob technique was an impossible to phantom.
 
I grabbed her hair and started to guide her rhythm. God she felt good... I looked down and had the most wonderful rush of power. She was mine now... I had felt similar rushes with Nichole and Tammy, but this was different.
 
As thoughts of the power I held over my 3 little vixens flooded my mind, I couldn’t help it anymore...
 
I came hard and shot my load in her mouth. Spur after spur... She took it all like a champ. A little semen came out from the seal her lips made around my shaft. I waited for her to finish licking it all up before I pulled on her hair and lift her head level with mine.
 
I saw her swirl her tongue around, slowly... My order for her to taste it before she swallowed seems to be working well. I watched her swallow. As she did, I was treated with a perfect view of her facial expression. The surprise on her face was priceless.
 
“So? How did it taste?”
 
“Fucker... It... It taste even better than your fucking milkshakes...” she said angrily.
 
“Why the long face then? Seems like you enjoyed it.”
 
“Bastard... You know why!”
 
“Hahahaha.... Fine... Let’s move to the living room.”
 
I let her go and got up. I knew we still had a few hours before my foster parents arrived so I decided to push things a little. We got in the living room and I undressed. She looked at me funny.
 
“What? I thought you would feel more comfortable if I was naked as well.” I said while sitting in the lazy chair.
 
“It’s not that... It’s just... Aren’t you... You know... Done?”
 
“Oh for the moment... But I think you’ll find I recover rather quickly.” I said as I winked. “Now kneel.”
 
I saw the defiance in her eyes for a moment, then she knelt. I crooked my finger to have her move between my open legs.
 
“Now... Since you like my cock so much, suck it again until I’m nice and hard...”
 
“OH COME ON!” she exclaimed.
 
But she grabbed my flaccid cock anyway and started to lick it. I stretched my arms behind my head and watched her work. It took a while, but my erection finally came back. I admit I didn’t concentrate on her work so much because I wanted her to work for it.
 
“You can stop.” I finally said. “Get up here and straddle me. Fuck me.”
 
“Please... Don’t make me do this...”
 
“Stop talking.”
 
She got up and I could see small tears start to form as she straddled me. I aimed my cock at her opening as she descended on it.
 
She was tight!
 
We fucked on the lazy chair for a long while. She came 2 times before I came. I had her clean me off with her mouth until I was hard again and fucked her a second time from behind.
 
We got cleaned up before the parents arrived. I told her she was to keep our new relationship a secret from everyone. That she would treat me kindly from now on and not show anyone if she felt different than usual.
 
I sacrificed my week to the project of my foster sister. I say sacrificed because I decided NOT to sleep over at Nichole’s and Tammy’s place. It was a nice change of pace. I sneaked into her room every night and most mornings. I managed to have her suck me off at least twice every day and we fucked 1 or 2 times after.
 
Once the weekend came around, it seemed like she had had enough doses in her to stop resisting my orders. She still wasn’t happy about the whole thing, but she accepted it.
 
I decided to make it 2 weeks.
 
A second week of multiple doses a day finally had their toll on her. By the time the weekend came around, she was mine. She would flirt with me when we were alone and even started to offer sexual favors between the ones I ordered her to perform. She even started to sneak into MY room early in the morning to wake me up with a blowjob.
 
It wasn’t too long after that I introduced Mindy to Nichole and Tammy.
 
My tests were done and I knew a lot more about how my spunk worked and how long it took. I now had 3 lovely slaves ready to do anything for me. It made for incredibly fun play at night as Mindy opened up and told us all about her curious experiences with women. Seemed she was already on her way to being bisexual.
As much as I was satisfied with my 3 beauties, I still had questions. Why was my spunk doing this to them? HOW was it doing it. It got me so curious that I changed majors and decide to branch off pursue a degree in organic chemistry. It was hard work, but my beauties were always there to help release the stress.
 
And to help me do more tests.
 
After 3 years, I had had a few conquests, but I didn’t ‘infect’ anyone else. I finally made a breakthrough and knew some of what was happening. My cum WAS different. It’s chemical make up was way off the charts. My little swimmers were different as well. I seemed I had 2 types. The regular type, and a completely different type. This new mutated sperm actually didn’t aim to the fertilize an egg, they aimed to fertilize brain cells.
 
I discovered that they entered the blood stream as soon as they could via any soft tissue. Then, they would travel to the brain. With each new batch of swimmers, more and more neurones got ‘fertilized’ and the brain pattern slowly changed and adapted to one that would view me as their Master.
 
As the one that had claimed them.
 
I had no idea why I had such intense and mind altering spunk, but I did. As I researched them, I realized that not all my mutated swimmers made it to the brain. The process of change was slowed down because of the way I exposed the women. A lot of sperm was lost or destroyed by the female body and didn’t reach the brain.
 
I spent a few months doing 2 things, first, I researched and tested ways to augment my own production and render each cum shot loaded with more swimmers. Especially the mutated ones…
 
And two, I spent that time collecting my spunk for the purpose of isolating and harvesting my special swimmers. After half a year, I had concentrated liquids of my boys in a formula I could inject directly into the veins. My thought being that it would minimize the losses.
 
How right I was...
 
I decided to do a test. By that time, I had been head hunted by a large chemical company and could use their facilities for my research. I got out an ad that called out for volunteers. It was to me a special type of research that would be done over the weekend. It paid 500$. The ad specified I needed women and that applicants needed to send a head shot. It said it was for anti-aging cream.
 
I got quite a few responses. I filtered through all the applications and found the perfect candidate.
 
Her name was Candice…​