I got this idea from reading some Ben 10 crossovers, with the Omnitrix being put to another character from something else, so I thought I should give it a try, enjoy.

The Omnitrix

In outer space, a battle was happening. The bigger ship began to power up a blast, as a monster within the ship, a humanoid squid man with red armor and long fingers. This is Vilgax, a man who wanted to find what ever is in that ship for awhile now.

He yells "FIRE!!!" making the smaller green ship explode, as a small black pod flew down to the Earth, towards the United States.

Camp Half-Blood. Long Island, New York

A large camp in the base of a few hills with a large Pine tree that looked like it could work as best Christmas Tree on the biggest one of the hills, and also a bunch of cabins in the base of the camp.

In the forest, a couple of teens were in the forest. One was Percy Jackson, the black haired, green eyed, Hero of Olympus with his girlfriend, Annabeth, the blond haired and gray eyed daughter of Athena. They heard something coming down and crashing onto the ground.

Annabeth asks "What in the Hades was that?"

Percy says "I'll go check it out." He was about to go until Annabeth stopped him.

"don't do anything stupid, Seaweed Brain." she said, as Percy left with a nod. She just sighs a bit and goes back to her cabin.

Deep in the forest

Percy looked around when he found the pod in the ground. He sighs a bit and asks "What is with satellites and crashing to earth?" he looked at it as it opened up, revealing a dark green and black watch with a strange symbol on the head area. He asks "What the?" He reaches for it and then puts it on.

"Nice fit, but maybe I should take it off." said Percy to himself, and tried to take it off, but it wouldn't do anything. "What the?" he asked, as he tried to pull it off. "Come on you stupid...COME ON!!" he yelled, and groaned as he gave up.

He runs back to the camp and runs into Grover Underwood, a curly haired teen with goat-like legs where his legs should be, along with blue eyes. He noticed the watch and asks "What's the watch for? A gift from Annabeth?" he smirked at the last part, making Percy blush a bit.

"No! Listen, I found this in the woods, and it won't come off." said Percy, showing he couldn't. He sighs a bit and tried to mess with the head, making it go up and shows a hologram of a strange creature. "What the?" He pushed it down and began to glow brightly.

Grover recoiled, and looked surprised at what Percy changed into. The teen changed into a dark blue and black moth-like creature with bug-like green eyes, a strange shaped mouth, three-appendages on his hands, three toes on his feet, the same symbol on his chest, along with a strange mist coming from him, along with a large pair of black and blue moth wings covering him like a cloak.

The strange creature yells in a raspy voice "BIG CHILL!" And looked himself over. "Okay, this is weird." as he flexed his new fingers, trying to wake them up.

Grover looks him over and looked nervous. "Percy? Is that you, dude?"

"Who do you think I am, G-Man? Ares?" asked Big Chill, looking around. Grover looked at him over as Big Chill asks "What is it?"

"Don't you notice your a bit different?" Asked Grover, confused.

"Minus my voice, I don't seem different, I don't think." said Big Chill, looking at himself. "Never mind. So, what do you think this thing can do?" He heard a roar from the forest and looked surprised to see Annabeth fighting a giant scorpion.

"Ah man, a giant Pit Scorpion!" yelled Grover, surprised. He looked behind him and noticed that Big Chill was flying towards the monster.

"Back off my girlfriend, bug-boy!" Yelled Big Chill, in a annoyed tone. Annabeth looked confused.

"Wait, I'm....Percy?" Asked Annabeth, confused. Big Chill nods as Annabeth gasped. "Oh my gods, what happened?"

"I'll clue you in later, now I need to take this scorpion down." He flies down and was about to grab his sword and noticed something. "what the? Where did Riptide go?" he started looking around.

"I guess that form doesn't have pockets on it." Said Grover, as Big Chill groans.

"Just great. What now?" asked Big Chill, as he was about to be stung.

"PERCY! LOOK OUT!" Yelled Annabeth, getting Percy's attention.

"Di Immortals!" cursed Big Chill, and covered his head, and waited for the sting and poison. He looked down and noticed his body was transparent.

"That's new." said the moth alien. He then jumps up and takes flight. 'I hope Zeus can make a exception to this.' thought Big Chill, as he flew around the monster.

"Do something!" said Annabeth, a bit nervous since the monster was getting close to clamping him.

"Time to see what this thing can really do." said Big Chill, smirking as he breathed out a blast of mist, encasing the Scorpion in ice. He then dives down and shatters the ice, making it turn into a pile of shards and golden powder.

Big Chill flies down and pants a bit. Annabeth and Grover came to him as Grover says "That was so cool dude!"

"Emphasis on cool." Said Annabeth, smiling. Big chill just did a sheepish smile, as if embarrassed.

Later

After Percy turned back to normal, he and his friends went to Jake Mason, the head of Hephaestus cabin.

Jake says "Well, this thing is new. And your telling me you found this thing in the middle of the woods?" he gives Percy a funny look, but the child of Poseidon just shrugged.

"Yeah, a weird piece of space junk came from the sky and I found this watch. I tried it on, and when I tried to take it off, it wouldn't budge." Said Percy, proving his point as he tugged at it, not moving a bit.

Jake asks "What exactly does it do?"

"It seems to change Percy's appearance at will, making him turn into some strange creature." Said Annabeth, looking at the watch with a funny look.

Percy says "Lets see how I can get this off." he motions Annabeth and Grover to come on, and they left with that, waving goodbye to Jake.

After a few months at camp, Percy and Annabeth were getting ready to go back to school, since school was about to start again soon.

Percy and Annabeth smiled, and got ready to go. After getting the strange watch, Zeus allowed the son of Poseidon to be able to fly as long it wasn't by plane, since some of his forms involved flight. Annabeth asks "So, what now?"

Percy shrugs and says "Well, it seems I got more then just Riptide to fight monsters, huh?" Annabeth laughed a bit a that.

In space

Vilgax growls as he says "Send some drones to get the Omnitrix, now!" A robot nodded and pressed a button.

A large droid was fired from the ship, going for the camp.

Camp Half blood

The droid landed and opened up, revealing it to be a giant robot with red robotic eyes, large black claws and three legs.

Percy and her were about to leave camp, but then they heard something attacking the camp. The droid was about to smash a cabin when a arrow whisted past it's head, and looked down at the Apollo campers. It aimed a energy beam at them, ready to fire.

Percy, ready for this, activated the Omnitrix. "You sure that's a good idea?" asked Annabeth, not thinking that was smart.

"That scrap pile will trash the camp other wise." said Percy, turning to a random alien before slamming it down.

He began go grow in size as a giant monster took his place. The monster was a 12-foot tall tanned Tyrannosaurs, dark green eyes, a long tail, sharp teeth, and also a mean looking muscle mass with the Omnitrix symbol on his chest. He then roars "HUMONGOUSAUR!" and runs down the hill.

Humongosaur growls as he says "Hey bolt-boy, your in the wrong place. Tokyo is 12,000,000 miles in that direction." the robot stared at the symbol on his chest. It aimed as Humongosaur says "Hey, what are you..." But got blasted, knocking him down.

"Okay, that does it." Said the dinosaur alien, growling. The Robot was ready to fight, as was Humongosaur.

End of Chapter 1

Well, that was a good start, don't you think? Well anyway, if anyone has any ideas for the story, feel free to leave it in either a review or a PM. Anyway please Read, Review and Suggest away!