A voice on the other side of the door replied, "It's Mark and Max. Can we come in?"
Looking at each other, the trio decided to allow them in, then got up off the bed to go unlock the door. Once unlocked, the door opened and Mark and Max came inside--and saw their father conjoined with their friend and his father, a three-headed body.
"Whoa!" Max exclaimed.
"Did you guys use that suit of Luke's? Dad, how come you got a turn with it and we didn't?" Mark asked.
"I didn't even know what that thing did at first, but then Ethan fused with me," Scott explained, "and then we took the suit off to fuse with Luke."
"And it looks like we interrupted a little fathers/son bonding," Max added, referencing the conjoined trio's lack of clothes.
"If you boys want, Scott and I could do this with all of our sons," Ethan smiled.
"Except Zack, since your younger brother doesn't know about this yet," added Scott.
"Alright," Max replied.
"Yeah, let's do it!" exclaimed Mark.
With that, the two twins quickly stripped down and piled their clothes--underwear and all--on the floor next to the bed. After shutting and locking the door again, the group readied themselves for another fusion. The twins pressed their backs against the trio's torso, as Luke and Ethan's fusion powers caused them all to merge. In less than a minute, there was only one body in the room, with six legs, five cocks, two arms, and five heads: from their left-hand to right, Scott, Max, Mark, Luke, and Ethan.
Now that all five of them were fused together, it was time to get back to their bonding. Lying back down in the bed, the five heads each began thinking of and concentrating on the things that caused arousal for them. In no time, all five cocks were rising and stiffening. It was disappointed at first that only Ethan and Scott had arms of their own, until Ethan and Luke used their powers again to grow two more right arms and one more left arm: with each of them controlling one arm, they were all able to grasp and rub their own cocks intensely. A series of moans followed, not of pain but of pleasure, as their rockets filled with their "fuel". Soon, all five were "blasting off," the cum streaming high before raining down in the shared torso, as the five heads panted, smiled, and laid their hands on their chest in relaxation and ecstasy.