Well, so far so good. I'd like to thank mdizzle for being the first to review, and I would like to thank shepyt and atlantiandragoness for being second and thrid. I apreciate your reviews! Oh, and to answer atlantiandragoness' question, Jake should be in the next chapter, or the one after.

I would like to say before I begin this chapter that I had once thought of a Danny Phantom Yu-yu Hakusho crossover but haven't written it yet. Despite that, this is the same universe as that so Hiei and Danny know each-other very well. Also, this also has elements from Fairly Odd Parents in it. Namely Chip Skylark is mentioned once and Chet Ubetcha is in the story starting next chapter. Also, this takes place 4 years in the future, so Danny, Hiei, Clover, Jake, June, Sonic, and Sora are all 18, 19(in demon years), 19, 18, 18, 17, and 18, respectively. I'm not sure if all those ages would be acurate, but that's how it is here. Anyway, enough of my nonsense!

I don't own any characters from any shows in this fic.

The next day, in Amity Park, Danny Fenton walked through the park with his girlfriend Sam.

It made Danny smile to think about how he used to deny his feelings for her, and how just 2 years ago he had finally gained the courage to tell her the truth.

"So, I guess your dad must be pretty proud of you, huh?" She asked.

"Yep." Danny replied. "It's funny though, mom and dad knowing my secret. Remember when they used to think I was as much of a threat as all those other ghosts?"

"I remember when the whole city thought that. It's weird the way things change over the course of 4 years. Now you're the hero of the city, everyone loves you, and soon you're going to be leading the Anti-Ghost force."

"Yeah, I just hope I can handle it."

"I'm sure you can Danny." Sam took his hand in hers. "You've faced the worst villains and monsters in the world, and you always managed to win. That's why I love you."

Danny smiled. But his smile turned to a frown when he sensed something strange.

"What is it?" Sam asked. "A ghost?"

"No," Danny replied. "It's… something else. I'm not sure what it is, but it's somewhere nearby." He moved away from Sam. "I'd better check it out. I'm going ghost!" Danny turned into his ghost form and turned to Sam. "Stay here and I'll be back as soon as I can."

Danny flew off to find out what he had sensed.

Meanwhile, at one of Fenton Industries laboratories, two mysterious figures worked at a computer, copying secret files.

Little did they realize that they were being watched.

Hiei looked through the window at the shadowy figures as one took a disk from the computer. They were heading toward the door when Hiei jumped in and blocked their way.

"That's far enough." He said, drawing his sword. "I'm not sure what you are, but you'd better tell me what you're doing here before I add you to the long list of creatures this sword has sliced through."

One of the shadowy creatures, which had yellow eyes and ant-like antennas, sank into a shadow on the floor which glided under Hiei.

The creature came back up and hit Hiei in the back of the head, temporarily knocking him down and giving both of the creatures the opportunity to run out the door.

Hiei chased them up to the roof, where another surprise awaited them.

"Hey," Said Danny, as he floated in front of the creatures. "Mind explaining what you're doing here? Or better yet, what exactly are you? You kinda seem like ghosts, but there's something weird about you."

One of the creatures lunged for Danny but he shot a beam of green energy at it, knocking it off the roof. The other turned to run but was cut in half by Hiei's sword, then vanished.

"Well, well," Hiei said as he sheathed his sword. "If it isn't the spirit detective's good twin, Danny Phantom."

"Hiei, long time no see." Danny replied. "And speaking of Yusuke, how come you're not working with him?"

"I'm on a mission for Spirit World, investigating a strange portal recently opened."

"A ghost portal?"

"No. It's a portal never before opened in this world."

"And I'll bet those things came through it. What were they doing here?"

"As far as I could tell, they seemed to be stealing files."

"Stealing files! Which one had the files with him?" It was then that they noticed the creature on the ground, who had only been stunned, sink into another shadow, taking the disk with him. "Please tell me that disk was Chip Skylark's newest album…"

"I'm afraid not."

"Oh man, my dad is gonna be so mad when he finds out."

"I think there's more at stake here than your allowance Danny." Hiei snapped. "I couldn't sense any kind of mind in those things. They were like empty drones."

"You mean they had no brains?"

"More like… they had no hearts."

"Whoa, kinda like a Tin-man."

"Yes, except the 'tin-man' wasn't being controlled by some dark force."

"So, what do we do next?"

"We?"

"Yeah, we need to figure out those things are, where they come from, what they want with the files and where they come from."

"Correction, I need to investigate the portal, you need to take care of the hero work."

"What? But Hiei, we need to work together on this." Danny shouted in frustration. "It's your job to investigate the portal, but it's my job to make sure this town is safe. And to do that, I need your help!"

"Might I remind you," Hiei replied. "That you were the one who decided to take on the responsibility of a hero?"

"Hiei, why can't you just help me? Be a team player for once!"

"Sorry," Hiei said, as he turned around. "I don't do teamwork."

Before Danny could stop him, Hiei disappeared.

Meanwhile, in a dark room in another part of town, the creature rose up from the floor and stood before a mysterious figure. It then handed the figure the disk.

"Well done." The man said. "Now the invasion can begin."

The next morning, Danny walked downstairs for breakfast. He had managed to escape telling his dad about it that night, but now there was no escape.

"Hi Mom, hi Dad." Said Danny, as he sat down.

"G'morning Hon." Mattie called from where she stood at the stove, cooking eggs.

"Good morning Danny." Said Jack, as he put down his paper. "You know, you got in kinda late last night."

"Oh, yeah, about that…" Danny began, nervously. "Ya see, I kinda had to make a stop at one of the Fenton Industries labs…"

"What for?"

"Well, these weird, heartless creatures had broken in to steal some files…"

"They did?" Mattie exclaimed, sitting down. "Did you stop them?"

"Of course he did!" Jack said proudly. "No ghost is a match for our son!"

"Um, ya see Dad…" Danny continued. "They kinda weren't ghosts… and one of them kinda got away… with the files."

"They… did… WHAT?" Jack jumped up from the table. "How could this happen!"

"I don't know. My ghost powers don't work on them the way they do on ghosts."

"Now Jack, calm down." Said Mattie. "It's not Danny's fault. We need to go over our files and figure out what they took."

"(Sigh) you're right Mattie." Said Jack, calming down. "I'm sorry Danny. At least ghosts didn't get their ectoplasmic mits on those files. Cause how could these things be any worse than ghosts?"

Jack and Mattie left the room to take a look at the files.

Danny was about to eat some breakfast, to try and ease his guilt, when a barrage of images suddenly flooded his mind. Images of doors, of keyholes, of light and shadow, of people losing their hearts, of worlds disappearing, and of a key…

When the vision finally stopped, Danny felt extremely confused. Something or someone was trying to get his attention.

Meanwhile, Hiei jumped from rooftop to rooftop. He had spent the entire night searching for the creature, knowing it would give him the answers Koenma wanted.

The sooner he finished this job the better!

Hiei was finally managed to track down the creature in a fairly large house. It was an easy task for Hiei to slip in and make a search.

He looked at an old picture on the wall of a man standing in front of some kind of portal. This was where the creatures came from all right, but who had brought them here? And what was his plan?

He then noticed a degree on the wall next to the picture. He read the name written on it and was actually surprised.

"Well what do you know?" He said to himself. "All along he was right under Danny's nose."

Just then he heard a noise. He turned around just in time to see several of the creatures. Except these were slightly different.

They were slightly taller than the two he and Danny had faced, and wore armor.

Behind them stood the mysterious figure.

"Dr. George Smith, I presume." Hiei said flatly.

"How nice of you to drop by." Dr. Smith replied. "I've never had the pleasure of meeting a demon before."

"I'm afraid I'm not here for a visit."

"Ah yes, no doubt you've been sent from Spirit World or something like that."

"Yes. Though I'm surprised a human would know about that world."

"I know about that, and many other worlds, like the one which I got the Heartless from. I could tell you all about them, but I have a lot of work to do." Smith was about to walk away when Hiei stopped him.

"You mean your invasion?"

The doctor smiled. "Yes."

"I see now. It's all a part of your plan. Opening the portal to allow more of these creatures in, so they can conquer the world for you. Very ingenious. And I'll bet those files you stole had something to do with Fenton Industries' plans for an Anti-Ghost Force."

"Precisely! You truly are an intelligent little demon!" Hiei raised an eyebrow at the word little. "But now I really must go. But don't worry, I'll leave these Heartless to keep you company. Farwell."

Dr. Smith left the room, and the Heartless closed in on Hiei.

He drew his sword and prepared for battle. Somehow this job had gotten a lot more complicated.

Okay then! Next chapter the other characters should start showin' up. See ya then.