The break from school for the summer also gave Charlene and Sis that much more time to spend together during the day… and no reason for them not to spend even more nights at one house or the other.
It was about the middle of July, and Dad had taken Mom on a promised date to listen to our town's little orchestra do a "Symphony in the Park". Charlene and Eva were at our house and had isolated themselves in Sis' room while I was watching a movie on TV. I'd figured that with the two of them back in Sis' room, I'd be able to watch the whole thing without interruption; but that didn't prove to be correct. Roughly halfway through the movie, the two of them came into the living room where I was and stood in their bathrobes off to the side just watching me. I finally paused the movie, turned my head to face them, and plaintively asked "What?"
After they'd looked at each other, it was Charlene that told me "There's something we'd like your help with."
"What, now? It can't wait until the movie is over, or tomorrow, or something?"
"No, not really", Eva answered. "It's something that we'd need to be sure Mom and Dad will both be out of the house for a while."
Wondering why they could possibly need me and Mom and Dad gone, I asked exactly that: "Why would you need me while Mom and Dad are gone? What's going on, Eve?"
Both of them looked nervous for some reason, but Charlene was the one to tell me "Come with us, and you'll see", immediately followed by both of them blushing furiously.
The looks they were giving me finally convinced me to do as they asked. After taking note of where I was in the movie, I shut it off, then stood up and followed them — all the way back into Eva's room, much to my surprise. Eva was the one to close the door behind us, and after she'd joined Charlene again, she told me "There's something that Charlene and I both want to find out, but neither one of us knows anyone that could help us with it… except you. We want to ask you something, and we already know it's a lot to ask, and we'll understand if you don't want to do it. But if you do, we're willing to do something for you in return."
Well and truly baffled at that point, all I could think of was to ask them "What is it you want from me?"
They gave each other a Look, then carefully faced me and undid the belts of their robes. Before I could even take a breath, they'd shrugged their shoulders — leaving both of them standing there stark naked with their bathrobes puddled around their feet. As I stood there (undoubtedly looking as stunned as I felt) looking the two of them over, Eva told me "We… we want to learn about guys. The, um, sex parts, I mean. Charlene only ever saw them on babies, and it's been a long time since we saw each other — I told her about it — and I know that I've changed since then, so I figured you have, too. That isn't something we can ask any other guy to do, so if you won't do it, we'll have to try and figure something else out. But if you'll agree, then it'd be okay if you wanted to do the same thing with me."
To that, Charlene added "You know I have little bit of a penis, but I've also got a vagina… so if you wanted to look at me, too, it'd be okay."
Eva finished up by telling me "We want to look close, and ask some questions, and… if it's okay, even, um, touch. However far it's okay for us to go with you, you can go with us. We figure that kind of encourages you to let us learn what it is that we want to know while keeping us from going too far with it. We're willing to trust that the time we spend looking at you will be about the same as you spend looking at us, but it's okay if you think we should actually keep track of the time."
Hearing that, the first thing to come to mind was that it actually sounded fairly reasonable. But a few more seconds thought, and I had a question: "You said that you were willing to trust that the time would be the same, but would my time be for looking at each of you, or both?"
They had some kind of silent negotiation thing using just their eyes before facing me again so Eva could tell me "There'd be the two of us looking at you at one time, but we know it wouldn't be fair for you to have to try to look at both of US, we'd be okay with it if you wanted to use almost the same time for each of us. It's not like we're completely different; after all."
That wasn't as much as I could hope to get, but was more than I'd have settled for… and easily enough to get me to seriously consider their offer.
Like most guys my age, there was a certain amount of trepidation at the idea of a girl (or worse still, two of them) actually eyeballing my works due to the basic insecurity most of us guys have at that age. But that was far overshadowed by the prospect of having those same girls doing more than just looking. When I added in the opportunity to really look (and touch, if they went that far) their parts… well, it didn't take me long to decide to agree to their request. Yeah, Eva was my sister, and that was kinda weird — but she was still female and attractive, and that was what was most important to me. Charlene left me with mixed feelings, though: the chance to check out another female was definitely enticing, but getting close to her snatch meant also getting close to what was above it — and I wasn't real wild about that idea, regardless of my acceptance of it otherwise.
It took a minute or so for me to work through all of that (and looking them over in the process) before I told them "Okay, I'll do it."
I could see that my agreement was met with a mix of emotions: relief that they hadn't exposed themselves to me for nothing, happy that they'd get to find out what they wanted to know, apprehension about (almost literally) opening themselves up to my exam, and nervousness (which I also felt) about the situation and what would happen.
Since they'd had me come into Evas bedroom, I figured that was where they wanted it to happen; with them already naked, there wasn't anything for me to do but take my own clothes off — a simple matter of slipping of my sandals, pulling off my T-shirt, and slipping down my walking- and under-shorts. I managed to quash the impulse to cover my cock and balls, choosing instead to simply stand there with my hands at my sides as I asked "Where and how do you want me?"
"Lay down crosswise on my bed, about halfway", Eva told me, with Charlene adding "If… if you could kind of lay with your knees at the edge and, um, open your legs, it would be better, too."
Without saying a word, I walked the few steps to where Sis' bed was and got myself arranged as requested. It didn't take but a single look at them to realize that paying any obvious attention to what they were going to do would pretty much mess things up, I simply put my hands behind my head and closed my eyes. To my surprise, it helped me relax a little bit, too. A few moments later, I felt as they joined me (though they were careful not to make any contact).
For the first few minutes, all that happened was that I heard a fair amount of whispering back and forth between the two of them as I felt them move around a little bit. I was starting to wonder if all they were going to do was talk when I felt a cool pair of fingers gently grip my flaccid penis and lift it up.
Without opening my eyes, I quietly told them "You don't have to be that careful about touching me. As long as you don't squeeze my balls, I mean my testicles, too hard, it's okay."
The grip on my penis got marginally firmer, but that was all the response I got.
Over the next little while, I felt my cock and balls being moved around in different ways by two different hands as Eva and Charlene asked questions and got familiar and comfortable with the male reproductive anatomy; the way they were going about it was enough to keep me from getting fully erect, though I did get as far as semi-erect under their touch. The amount of movement had tapered off when Charlene hesitantly said "We… we'd like to see it when you're, uh, hard, too. Can you do that?"