I tried to relax, but I couldn't help tighten up as he eased into me. As soon as the head entered, I let out this deep, guttral yell from god knows where within me. My fingers dug deeper into the floor. I opened my eyes and looked down at James' face. He told me to just relax, but I couldn't, it hurt like hell going in, but I wanted more. The head passed and I squeezed with enough force to clamp a steel pipe in half. I strained, I grunted, as my body adjusted to having part of another person inside of me. Finally, I was able to take in about 3/4 of his length.

"I-ngghhh-don't know if I can do this. It feels kind of good, but kind of uncomfortable."

James looked confused for a moment, then a smile crossed his face. "God, I'm sorry man. Here, just a second, this should make it easier-- another benefit of this huge thing."

He closed his eyes for a second and I felt him flex and swell a bit inside of me, then I felt a warm, soft sensation, as he began to pull out-- I went nuts, I almost came right there.

"Oh- oh god... what did you... is that--"

"Yeah, I can control the amount of precum I produce... well, I mean, you can, too -- is it more comfortable?"

"Oh yeah... It's--" he thrusted into me again, deeper and smoother this time. "Agghhhh... bett.... nhhhhh... better."

He kept moving in and out, driving me insane. I couldn't think straight, I just started thrusting my ass into him, helping him go in farther. There were a couple of times he got in to the hilt - it hurt again, but in a much better way this time. He took his right hand and pressed my cock in the cleft between his pecs.

He nodded to me and I knew what to do. I strained a bit and felt the clear fluid start to flow. My god, that felt amazing, it slid so easily and felt so sensitive-- even that had been enhanced by the supplement.

All of this was beginning to be too much-- being filled by a thick thirteen inches, surrounded by huge muscle, being pec-fucked-- I already felt myself getting close. I could feel my balls beginning to swell again and my body tense up. James could tell what was coming and he stepped up his thrusting. Pretty soon, he was close to the edge, too. I could feel mine cresting, building-- I could feel him swell inside me slightly. We locked eyes for an instant. Then we exploded.

I screamed and my whole body shook-- every muscle flexed huge and hard. I blasted a torrent of cum right into James' face, as he opened his mouth to take some of it in. I felt a flood of his juice fill me inside, then flow down and out, around his shaft. I looked down, he was flexed, too, every massive muscle standing out in relief, every striation. I just kept cumming and cumming, I couldn't shut it off and I could feel James still going inside of me. If anyone had walked in, it would have been insane-- two huge bulging masses of muscle, conencted, yelling and grunting and shooting thick streams of milky liquid.

Finally, after about five minutes, it stopped. I collapsed on his chest. I felt him slowly draw out of me, the head emerging with a slightly wet quiet pop. I rolled off of him onto the floor and on my back, spent. It was quite some time before either of us could speak.

"You do this often? With that scientist guy?

"Every two weeks or so."

"Holy shit."

"You like it?"

"I'm still trying to get my mind around this, but, um, yeah."

"I thought so. Well, let's get to work, we have about half an hour before we have to take care of things again."

"What?"

He got to his feet then helped me. "Yeah, makes the whole process not very practical. My friend's working on it, though." I got to a standing position, still a little unsure of my footing. I was already getting hard all over again.

"Okay, what's first?"

The rest of the day was incredible. I was lifting piles of boxes, stacks of stuff like they were nothing. I carried the refrigerator out on my own. A freaking refrigerator. I was so turned on, I had to jack about three times afterwords. We loaded up his heavy-duty truck, threw on some way too small extra clothes he had for modesty's sake and went over to the new place and moved everything in. It just felt so good, using this new body, feeling every muscle flex and bunch up, feeling the sun on my naked body-- god, it was amazing. Oh, there was the four more sessions of hardcore sex with James, too. Three more at his place and another at the new one, to christen it.

Around nine that night, I was helping him rearrange some things, feeling him up, when I started feeling weird, shaky. James helped me to the couch. I could see the same thing was happening to him.

"Don't worry," he said. "The stuff's just wearing off, it'll pass in a minute or so- unhhh.." He dropped to the floor.

This feeling of fatigue hit me, I couldn't move anything. Then, I tensed up and could feel myself deflating-- my skin sliding against the couch, as my body returned to normal. The heat from the dissipating energy or mass or whatever filled the air around me, it was almost stifling. Then it was over. Just like that. I pulled myself up and I ached all over, covered in sweat. James was sitting there, next to me.

"You okay?"

"Yeah, I think so. Just kind of sore."

"Well, your body's been through a lot. Just drink lots of fluids. Actually--" He got up and went into the kitchen, sidestepping huge boxes that seemed small only minutes before. I felt kind of cold and self-conscious. I wrapped myself in a nearby blanket.

"Hey," he yelled from the kitchen, "were you going home tonight? You can stay over, you know? If it's too late and you're tired."

"um, well-- I don't know. I mean, what we did--"

"If you're uncomfortable, you can sleep on the couch, that's cool. Or- -" He came into the room, with two glasses filled with what looked to be fruit juice. "We can stay up a little longer."I shrugged off the blanket, took a glass and smiled. "I guess I could stay for a nightcap. So, when's the next time you and your scientist friend are getting together?"

"Next weekend. I already told him about you, said you'd probably be interested after this weekend. He'd really like to see the effects on another person."

"Well, anything for science," I said as I downed the supplement. I could already feel myself getting hard... •