A/N: Hello, my lovely readers! This is my Ben 10/Danny Phantom crossover. For Ben, it takes place during Alien Force, and for Danny, it is in season 3 but before Phantom Planet. Also, press for Danny Phantom occurs only in Amity Park, not other places. In other words, Ben and Danny's powers are not known to the public.

Please leave reviews and enjoy!

-E

Disclaimer: I do not own any content from Ben 10: Alien Force or Danny Phantom.

Agent Harangue was sitting at his desk for a cup of hot coffee. He was a tall, muscular, and generally intimidating man, with an expression that was constantly stern. He held a position of authority in his department, for which he had worked many years, as it showed on his face. He took pride in his work. Not once had he been evaded, and he planned to keep it that way.

That morning, he was interrupted by one of the younger agents. The man simply said, "We've got him, sir."

Harangue straightened his posture, alert. "Confirm his exact location. We'll need to devise a plan. Tell them downstairs that Project Decagon is in operation."

"Yes, sir." The young agent left.

"We will find you, Ben Tennyson," he muttered to himself, his lips almost curling up into a smile. "And we will find out what you are."

Ben smiled as he inhaled his blueberry-ginger smoothie. Julie's hand felt warm and soft in his, like it was made for him. He looked over and studied her face. Every feature seemed perfectly crafted. She looked at him and smiled. He loved it when she smiled. She opened her mouth to speak, and…

"Remember, Ben, physics isn't that hard. You just have to think about logically. And stop stressing about the test. I'm sure it'll be fine."

"Easy for you to say," he replied. "You've had straight A's since kindergarten."

"Hey, now. Let's not make assumptions."

"I'm just saying. It's true. You're, like, a supergenius. I bet you…" Ben trailed off. He was quiet for a couple seconds, and then slowly raised his hand to left wrist. Julie seemed to catch on immediately. Her eyes widened at the massive robot before them.

Ben adjusted the dial, and slammed down on the Omnitrix. He felt the awkward but all too familiar sensation of his DNA morphing. He grew shorter and sprouted a couple more arms, and blue fur grew rapidly all over his body. When the transformation was complete, he yelled, out of habit, "Spider Monkey!"

In this new body, Ben 10 analyzed his opponent. It was around nine feet tall, and perched on four mechanical legs. It didn't seem to spew lasers, fire, acid or poison, but Ben knew to be prepared for anything. The steel beast walked toward him, forcing him to back up until he hit a wall. For a moment, he just stood there, unsure of what to do, when he spotted a lamppost ten feet away.

He jumped with all his might, swung around the lamppost, and used it jump atop the robot's flat head. He looked for any sort of opening, where he could pull some wires, but there were none that he could find. Meanwhile, the robot was walking into an alleyway. Ben decided it was probably a good time to dismount.

He landed face-to-face with the robot. Without missing a beat, he spin some thread and wrapped it's four legs together. The machine toppled, and the lights on it went dark. For a minute he waited for any signs of reactivation, but there were none. "That was almost too easy," he muttered to himself. Naturally, he had spoken too soon.

In a heartbeat, men in black jumpsuits and helmets holding guns lined up on either side of the alley. Bewildered, Ben started to raise his hands, which were shaking. "Now guys," he said, "I don't want any trouble. I'll just go now, and we'll pretend this never happened." But before he could anchor a web to the building beside him, he felt the pang of a dart pierce his shoulder.

Starting to feel drowsy, he pulled out the dart. The end that hit him was a sort of syringe, and the other end had a red fluff, like a mini feather duster. "Tranquilizers…" he murmured. "Great."

Ben sank to his knees, and his form transitioned back to human. He was really feeling groggy now. Behind a row of black-jumpsuit-guys, he spied Julie, in her pink hoodie and white tennis skirt. Run, he mouthed. She looked petrified, but his expression must have convinced her to comply. She looked back one more time. They shared a silent exchange, and Ben's vision blurred as her form ducked around the corner.

He felt two men grip his arms as he became weaker. They started to drag him towards a black van at the other end of the alley. Another man in a black business suit was waiting there, seeming to be the one in charge. Vaguely, Ben heard one of the soldiers ask what they should do about the girl.

"Leave her," said the boss. "We have what we need."

Ben wanted to struggle, but he could not. The van doors opened, and everything faded to black.

Again, guys, please review. I appreciate constructive criticism. Thank you!