You walk over to the Hero costume. It's way too big for a couple of kids to fit in.
"I want to try this, but I think I'll need to sit on your shoulders," You say holding up the hero costume.
“Do I really have to be on the bottom?”
You nod your head. Alex shrugs. “Fine, you can be on top.”
Alex starts to take off his clothes. ‘What are you doing!?’ You ask covering your eyes.
“What? I just thought it'd be better if it was skin to skin contact.”
You want to argue but, decide to not waste time and take off your own pants and clothes. Thankfully, no one sees you two in the back part of the store undressing.
Once undressed Alex steps into the leg part costume of the costume as you hold it open. Once he's in, he kneels and asks you to climb on.
You happily hop on his neck and press your groin into the back of his head. Alex stands up still holding a part of the costume.
"What are you waiting for?" You ask.
“Just wait a minute. I need to hype myself up for this first. We don’t know what happens next,” Alex responds. He took a deep breath a started to zip up the front of the suit. As he starts to reach the top, the suit becomes form fitting. Alex nervously hands the zipper to you to finish up sealing Alex in with your lower body.
You feel Alex move around inside the suit and under you, but it doesn't last long. You look down and you see the suit is gaining bulges in different areas. "Alex!" you shout but there's now response.
You feel your entire body below your neck disappear for a split second. Then, after the moment is up you feel sensations start to return. You look down at suit. It's no longer in the shape of two young boy's, but a body being formed. You hear you bones lengthen and watch as muscles shift around and grow tight under the skin-tight suit. Your chest expands as your arms and legs finally bulge out filling the suit completely. Your ass juts out firm, harder than a rock, while the outline of your growing cock is quite visible.
The zipper that was once on the front of the suit fades.
You feel a rush as, the veins in your neck bulge out. Genes from Alex are being deposited and mixed into your face. You grow older and your voice drops a few octaves deeper. You're overtaken by pleasure.
You try to grab onto a wall to stabilize yourself but, you just break through it.
You end up on your knees your monster cock nestled right between your Pecs. You start cumming gallons of super cum into your suit. Luckily your suit is built for challenges like these and quickly absorbs it.
"Alex did you feel that?" you say coming down from your high.
When you don't hear a response you panic a little, " You hope you haven’t drowned him in all the cum you let out."
Looking down at your body however you realize, you're the only one in the suit.
You frantically run your hands over you new adult body, calling for Alex's name to no avail. You rip the chest portion of your suit open, only to reveal a muscular naked body and hard cock pointing up at you. The suit reforms itself back together. Your stunned in disbelief, Now the super suit was adapting to handle all the wear and tear an actual superhero would go through wearing it.
Silently you start to let tears run down your face. You were about to call for Alex again when your pec's suddenly flexed, your ass clenched, and you cock jumped under the restrains of the suit.
All of Alex had been reconstituted as muscle and mass for the new combined body. Being the lower half Alex had the pleasure of being the meat that everyone else could gawk over, while you got the real pleasure of being 100% in control.
With your super hearing you hear a cry for help! But you know you’re the one that needs help if you're going to get Alex back. Perhaps you should go get you Uncle Jack?