Mark starts to look a bit distracted, and begins to reach to put on the blue, used condom.
"EW! I've already worn that one, bro!" you exclaim, impulsively. You know it probably doesn't matter, at least the old you does, but the Scott part of you finds the idea of your own brother putting something on his dick you just had on YOUR dick a little while ago disgusting!
Mark blinks.
"Uh, yeah, I guess your right," he replies, tossing the electric blue rubber onto your bed. He hesitates a moment, then seemingly grabs one at random-- a green one from somewhere in the middle sized ones.
You think that the lube must be effecting him, since he hurriedly tears the wrapper open. Worriedly, you notice that the condom seems to already be about the same size as your brother's now erect member. What if putting on one already your size won't make you change? Maybe you should have let him put on your old, blue one. Maybe he would have turned into your twin brother, which, come to think of it, would be kind of neat...
"OH MY GOD, am I HORNY!" Mark moans, grabbing his member.
YUCK! He's going to jerk off right in front of you! You start to turn away, but then notice he's starting to look a little different. It's hard to notice, but... Hey! Now you have to look up at him a little bit more! He's getting taller!
Mark seems to be lost in his, uh, "self-pleasuring," and does not seem to realize he is experiencing a growth spurt. His legs seem to be the first parts to be effected, with the thighs stretching first, then the lower legs... Wait, his abdomen is also stretching! Mark's legs and stomach now seem almost comically lean, like he's been stretched-- and he isn't done. His chest is now elongated, and his arms are stretching... and so is his neck.
Mark is now stroking himself faster, apparently nearing climax. As he is doing so, he continues to grow, now being somewhere over six feet tall, and he begins filling out his new height. Lean muscle starts to form under his skin-- not bodybuilder like, but more, well, like he had at his old height. A high school athlete who spends some time in the weight room. Then he gets just a little more, like a more serious athlete. His hair gets short, actually making it more like your own hair. Huh. He keeps growing, but keeps about the same amount of muscle-ness, or whatever the term is. (Hm, did you know the correct term before your transformation, or did you lose it as part of being regressed to a kid just starting junior high school?)
Suddenly Mark cums, letting out a moan. Good God! You get distracted by the amount of cum he spurts into the condom! You wonder if some day you will put out that much..., er, if you used to put out that much.... Then shake your head. Did you have this short an attention span as a kid, or is it unique to being Scott?!?
As Mark's breathing returns to normal, you notice that he is somewhere over six feet, six inches tall. Actually, he's probably somewhere around six feet, eight inches to six feet, ten inches. Almost as an after thought, his clothes adjust, his shirt sliding down to cover his stomach, his shorts becoming a bit bigger. You realize that you now seem to remember him being really into basketball, and good enough that he will probably be heavily recruited when he gets to be a senior. He is still age sixteen, though, and still your brother, Mark.
"See Squirt, I'm still the same guy," he says, now looking a bit embarrassed at having played with himself in front of you. "Nothing happened."
"Are you kidding?!" you ask incredulously, gesturing at him. "Look how tall you are?! And didn't you used to really be into lacrosse instead of basketball?!"
A look of shock and confusion comes over Mark's face. He looks himself up and down. He pulls up his shirt, and stares at his now six pack, nearly eight pack, abs. Turning around slowly, he takes in the room from his new perspective.
"Wait," he says, hurriedly pulling his pants back on. Mark leaves the room, and you hear his bedroom door open and close. A minute or two later, he re-enters you room, slowly.
"Holy fuck, little bro! Where did you get these things!? All my lacrosse stuff's gone, and I'm now some sort of basketball stud!"
He sits heavily on your bed, hurriedly moving when he realizes he just sat on the condoms. More careful, he repositions himself next to them, staring at the colorful collection as if he is eying an atomic bomb.
"Like I said, I was some adult guy, and someone left them in a black box, like a present, at my door, with a note," you explain.
Mark looks up at you.
"A note?! You didn't say anything about a note!" he exclaims.
"Ye--," you begin, then think a moment. Crap. He's right! You left out that minor, but maybe major, part of the story. "Yeah, it said something like 'Meet me in the park by the fountain at eight.' And it was signed 'Your Secret Admirer.' I think I've still got it, maybe. These things have been tele--,tel--, er, moving themselves all over the place. Plus my whole life's changed, kinda like your room."
Mark looks like he might not want to believe you about your life changing, but restrains himself. It occurs to you that your "big brother" might really like you, and not want you to go away. You realize you have conflicting emotions about going back to your old self..., although the fact that those memories seem to be getting dimmer really creeps you out!
You realize Mark is talking. He's found the note, and apparently read it.
"Huh?" you ask. Not the sharpest sounding thing to have said...
"I was saying, maybe we should check that out," Mark repeats, rolling his eyes slightly, like he does when he thinks you are acting "like a kid." "Or, maybe you could put one of the bigger ones on, although, I really don't know which one would turn you back to whoever you were before. I'm still me, mostly, after all."
You stare at the condoms. Will one of them turn you back? Or will you become yet another person? It's getting kinda close to eight o'clock, maybe you should head for the park. Does the note mean one with a big fountain, or one with a drinking fountain? You hope its the first one, because there's only one of those anywhere close to where you live, but a lot of the second type!
You think for a moment, then decide...