"Well we really need to try us out outside, but I'd rather know first how long this is going to last", Guy said as he was changing back his arm. Hiro nodded, "Yeah wouldn't want you to change back while in flight". He added "I've heard of an abandoned military base a couple of hours from here, nobody is there, not even during the day." "Sounds like a plan", Guy replied as he changed back his hind wheel into his crotch.
Hiro ran is engine idly as he reached towards Guy's crotch rubbing the bulge. He tried to open his friend's pants, but that didn't work, "Hmm, must be because your clothes are part of your body now.". He tried the zipper and it worked. Guy gently churred as his friend was doing his work down there. Gradually his member poked through his sheath, becoming larger and larger as Hiro started to lick it.
As Hiro changed back his clothes became less and less fitting, causing him to wake up. Half asleep he undressed and woke up Guy, who was still a raccoon, "Wake up, I've changed back". Guy quickly realized what was happening and asked Hiro, "How long?". Hiro looked at the clock and calculated, "About 6 hours... seems like a fair time" before flopping back to sleep snuggling his fuzzy friend.
The next morning the two found themselves changed back and naked again, they undressed and quickly had a bit of breakfast. "So tell me about this base you've been talking about", asked Guy. "Well it's out there in the desert a couple of hours away, I think they have a runway and a few hangars are still standing." They packed some food and drinks, and of course the potion and drove to that base. It was roughly a 3 hour drive over desert roads which looked like they haven't been used for ages. When they finally arrived they droved through the gate which must have rusted away years ago. They parked their car in one of the hangars which looked like it would hold at least for a couple more hours. "So, this is it", Hiro said as he started to undress himself, "I told you nobody was coming here." "Say...", asked his friend, "How about we rub each other instead of doing it individually?", and both grinned as they were standing in front of each other.
They reached into the pot and playfully and teasingly rubbed each other with the potion. Guy grinned and shoved his erect member into Hiro's ass after having rubbed it with the potion. Hiro shivered in ecstasy as his friend entered him. Guy started to piston his member in and out of Guy's ass shooting load after load into his friend while becoming slimmer and slimmer blissfully flowing into Hiro before completely dissolving into his friend who had gained his mass during that process.
Gradually Hiro's knees started to bend, forcing them down to the ground. Between his legs a wheel started to form. His neck disappeared and his head and body combined into the single plastic shell of a superbike. It had a special paintjob resembling a fighter plane. It was blue green with grey parts looking as if the paint had flung off. Near the engine there was a red circle with a yellow border. All metal and plastic parts were pained with mock rivets holding together mock pieces of metal. The seat was made from a much lighter shade of grey than usual. Overall it looked like a Susuki Hayabusa painted to look like a war bird.
Suddenly Hiro came back to his senses. He couldn't move, just like when he was a motorcycle before. He tried to look around for Guy, wondering where he had been left, before he cried out for him, "Guy! Where are you?". Suddenly a reply came back, "I'm here... I think I've joined with you. I can't move."