This idea has been stuck in my head for the longest time now! A Ben 10 TMNT Crossover! This one is with the current Teenage Mutant Ninja Turtles shown on Nickelodeon, but I do plan for Ben to be mutated later on in the story. I just haven't decided on what kind of animal I should use. But I do have a few ideas for what Danny's weapon should be. He won't just be relying on the Omnitrix in this story, so he'll have more versatility.

Pairing: Ben T. x Karai

Disclaimer: I don't own Ben 10, or Teenage Mutant Ninja Turtles!

"Normal Speech"

"Thoughts"

Songs

"Yelling"

Alien Database

Prologue: Terraspin vs. Razar!

In the streets of New York City, a lone teenage boy was walking through the streets with a depressed look in his eyes. He was wearing a black and green shirt, khaki cargo pants, and a pair of white and green sneakers. He had lightly tanned skin, messy brown hair, and green eyes. He was also wearing a sleek wristwatch with a square faceplate that was black with green buttons, and a green hourglass design. This is Ben Tennyson, former hero of Bellwood.

Now many of you may be wondering why I said former hero. Well, he decided to quit the hero gig after he was kicked out of an intergalactic police force calling themselves the Plumbers for no reason. And to make matters worse, his parents kicked him out of the house and practically abandoned him!

In response to this, Ben turned into an alien transformation that he calls Jetray, and flew out of Bellwood as fast as his wings could take him! In his anger and sadness, Ben flew for what felt like days but in reality was hours. Finally, he had landed in New York and turned back to normal. So here he was, walking around in the alleys of the city with nowhere to go, and no family to turn to.

As Ben walked along the path between two buildings, he couldn't shake the feeling that someone was watching him. And he would be right, as a pair of glowing red eyes was watching his every move. Ben stopped when he heard animalistic growling coming from the trash cans behind him.

He turned around thinking that it was a stray dog looking for a good meal, but what he saw almost made him go into a panic. It looked like a cross between a human and a wolf with glowing red eyes. It was clearly male, and had a build that was almost skeletal. He stood on his hind legs, had no tail, and was covered in dark brown fur that was almost black.

"Well, well, well. If it isn't the famous Ben Tennyson. Why would you be here in New York?" asked the mystery wolf.

"Don't call me Tennyson! I'm no longer a Tennyson, nor am I a Plumber!" Ben said.

The wolf thing seemed to chuckle maliciously as he got into a battle stance. Ben activated the Omnitrix, and a green wheel appeared. The wheel had the faces of his aliens on it, and spun until it stopped on the face of a humanoid dinosaur. He lifted his fingers, and the faceplate slid open to reveal the core.

"What's your name anyway?" Ben asked. "I like to know the names of the people I'm fighting."

"My name was once Chris Bradford. But you may call me... Razar!"

"Well then Razar, let's see you take on Humungousaur!" Ben said.

He slammed his hand on the Omnitrix core, and transformed into an alien. However, it wasn't the one that Ben was hoping for. Ben turned into an alien that looked like a cross between a sea turtle, and a tortoise. Its head was mostly in its shell, his arms were replaced by huge flippers that were the same as those found on sea turtles, and his legs were like those of a tortoise. He was mostly green with a yellow and brown shell that had six big holes in the front of the torso area.

"Terraspin?!" Ben said in a gloomy voice. "Great. I'll turtle him into submission!"

Alien Database Entry

Species Name: Geochelone Aerio

Given Name: Terraspin

A near extinct species of alien that is similar to turtles. However, these guys are a lot stronger than they look. By retracting their head into their shell and merging their legs into a third flipper, they can spin like a giant fan to release gusts of gale force winds to literally blow away the competition! And like regular turtles, Geochelone Aerio's are capable of retracting their heads and limbs into their shells for extra defense, and house a set of retractable claws in their flippers!

But wait, there's more! Geochelone Aerio are also capable of using miniscule amounts of magic. This in turn makes them invulnerable to an Anodite's mana based attacks! They can also release tornado force winds from the holes in the front of their shells, making it real tough for enemies to get in close for an attack.

Yet despite these awesome powers, the Geochelone Aerio are not invincible. They are a pacifistic race, and prefer to settle their disputes with diplomacy rather than actual violence. They are also not very fast when running, and can also be corrupted if they absorb too much magical power.

Razar didn't know what this form could do, but he had to be careful. One wrong move, and he could be defeated faster than he could blink. And it seems like Terraspin was about to make the first move! Three claws shot out of each flipper, and the turtle alien charged at Razar.

But the wolf mutant was more than prepared to handle hand-to-hand combat! He countered Terraspin's strikes with a few jabs, chops, punches, and kicks of his own. The two kept at this until they ended up outside of the alley.

That was when things went downhill for the canine mutant. With more room, Terraspin was able to use his aerokinesis abilities to the fullest, and use them he did! He retracted his head into his shell, merged his legs into a third flipper, and began to spin them like the blades of a giant fan!

This caused gale force winds to kick up, and made Razar lose his footing. The dog alien almost went flying away, but he managed to hold onto the ground with his clawed hands.

"Grrr! YOU... WON'T... BEAT ME!" Razar declared.

He tried using his claws like hooks to pull himself closer to his enemy, but the winds were growing ever stronger. Razar couldn't hold on any longer, and ended up getting blown away to the farthest part of New York! The Omnitrix started to beep, and in a flash of green Terraspin turned back into Ben.

Unfortunately, it had been so long since Ben had used Terraspin's wind powers to such a degree that he ended up passing out in the street. But it wasn't long before five figures surrounded him, and one of them reached out to Ben as the screen faded to black.

There's the prologue for you guys! I hope you all like this story idea, because I really think that this story could go big! Now in case you guys are wondering, this story takes place shortly after the turtles rescue Karai. Anyways, if you have any ideas for a kind of ninja weapon Ben should have, feel free to let me know what it is in the reviews! Thanks, and enjoy!