Disclaimer: I don't own Harry Potter. I'm just an obsessed fan mutilating JK Rowling's work.
Author Notes: I kind of got the idea of this story from the Star Trek episode The Enemy Within. This story starts with Harry using the Floo powder for the first time. All italicized text is from Harry Potter and the Chamber of Secretes.
Chapter 1
"W-what am I supposed to do?" he (Harry) stammered.
"He's never traveled by Floo powder," said Ron suddenly. "Sorry, Harry, I forgot."
"Never?" said Mr. Weasley. "But how did you get to Diagon Alley to buy your school things last year?"
"I went on the Underground -"
"Really?" said Mr. Weasley eagerly. "Were there escapators? How exactly -"
"Not now, Arthur," said Mrs. Weasley. "Floo powder's a lot quicker, dear, but goodness me, if you've never used it before -"
"He'll be all right, Mum," said Fred. "Harry, watch us first."
He took a pinch of glittering powder out of the flowerpot, stepped up to the fire, and threw the powder into the flames.
With a roar, the fire turned emerald green and rose higher than Fred, who stepped right into it, shouted, "Diagon Alley!" and vanished.
"You must speak clearly, dear," Mrs. Weasley told Harry as George dipped his hand into the flowerpot. "And be sure to get out at the right grate..."
"The right what?" said Harry nervously as the fire roared and whipped George out of sight too.
"Well, there are an awful lot of wizard fires to choose from, you know, but as long as you've spoken clearly -"
"He'll be fine, Molly, don't fuss," said Mr. Weasley, helping himself to the Floo powder, too.
"But, dear, if he got lost, how would we ever explain to his aunt and uncle?"
"They wouldn't mind," Harry reassured her. "Dudley would think it was a brilliant joke if I got lost up a chimney, don't worry about that -"
"Well ... all right .. you go after Arthur," said Mrs. Weasley. "Now, when you get into the fire, say where you're going -"
"And keep your elbows tucked in," Ron advised.
"And your eyes shut," said Mrs. Weasley. "The soot -"
"Don't fidget," said Ron. "Or you might well fall out of the wrong fireplace -"
"But don't panic and get out too early; wait until you see Fred and George."
Trying hard to bear all this in mind, Harry took a pinch of Floo powder and walked to the edge of the fire. He took a deep breath, scattered the powder into the flames, and stepped forward; the fire felt like a warm breeze; he opened his mouth and immediately swallowed a lot of hot ash.
"D-Dia-gon Alley," he coughed.
Harry felt like he was being ripped apart. It was frighting. It didn't help with the fact he felt like someone else was in what ever he was with him. The pain he was in had gone away and he landed face down on a hard floor.
"Harry? Are you OK?" Mr. Weasley panicked as he rushed to Harry.
"Just dizzy..." Harry replied. "Does Floor powder hurt like that?"
"What do you mean?" Mr. Weasley asked concerned.
"I don't know how to describe it but it felt like I was being split in two and there was some else there... Then it went away and I felt dizzy..."
"I never heard of anything like that happening with Floo powder... But at least you are ok." Mr. Weasley said wondering.
Soon, the rest of the Weasleys joined them and they proceeded to go shopping on Diagon Alley.
Lord Voldemort's existence was miserable. He had heard from Severus Snape about a prophecy that said a person who would be born at the end of July who would vanquish him. He decided to act on the prophecy and kill the most likely person the prophecy was about: Harry Potter. However, thanks to the interference of the boy's mother, he could not kill the boy. Next thing he knew, he was without a body and was being sucked inside the boy. He was aware of the boy's thoughts. He saw, heard, and felt everything the boy did. But no matter how hard he tried, he couldn't control the boy's body. Every time he did, he felt sharp intense pain. After a couple of weeks of trying, he gave up and admitted the boy had vanquished him as the prophecy said would happen.
When the boy started Hogwarts, he learned that Snape appeared to have betrayed him and that there was another him that was living like a parasite off of a stuttering idiot. He then released that he was a horcrux and that the other him was the main part of his soul; the part he had planned to keep inside of his own body.
When the boy went home to those awful muggles, he began thinking of how he could get the attention of the main part of his soul. The main part of his soul was without a body. If they could work together, perhaps they could kick Harry out of his body and they could use Harry's and become one again. It would be a lot easier then creating a new one. Not to mention demoralize the Wizarding world when he is discovered.
He continued to think of a way but couldn't help but watch Harry as messed up on using Floo powder. He mentally cursed the boy for causing him so much pain. Suddenly, he found himself face down in the fireplace at Borgin and Burkes.
"Idiot boy doesn't even know how to use the Floo properly." Voldemort muttered to himself.
Something didn't seem right. The boy's lips moved when he said that. Voldemort decided to try something. He decided to see if he could get the boy to stand up. It worked.
"How could this be?" he said to himself. He tried to see if he could sense if Harry was still inside of his body. Harry was gone. Somehow during the trip to the Floo, Harry's own soul was destroyed he thought to himself.
"Excellent." Voldemort said to know own other them himself and proceed to walk out of the store. Now, if only he could find the main part of his soul and contact his Death Eaters that still were still free. He saw Lucius and Draco Malfoy heading towards the shop.
"Got lost Potter?" Draco mocked.
"Now, now, Draco. Be nice." Lucius said in that eerie voice of his.
"Ah, Lucius. This is a pleasant surprise." Voldemort said. He didn't expect Lucius to recognize him. After all, he looked and sounded like Harry Potter.
Lucius looked a little shocked.
"I beg your pardon?" asked puzzled.
"Lucius, this may sound hard to believe but Harry Potter has apparently died in a Floo powder accident and after ten and half years I finally have body I can control."
"My lord?" Lucius said eying Voldemort suspiciously.
"Yes, Lucius. It is me. If you aren't convinced you can take me to your manor and question me endlessly until you are convinced. Either way, it would be nice to go there and meet with the others."
Voldemort knew he eventually would have to return to the Weasleys but he knew that his Death Eaters would want to spend some time catching up. He just tell them he got lost and ended up going all over the world.
"Yes my lord. Draco, I'm afraid we can't shop for your school supplies today. Maybe tomorrow." Lucius spoke.
Lucius, Draco, and Voldemort then proceeded to the nearest Apparition point.
Dumbledore was in his office alone as usual. With the exception of the report from his friend Ms. Figg telling him that the three youngest Weasley boys had obtained a flying car and showed up at 4 Privet Drive with it, the summer was seeming to be a typical one.
Suddenly, the door to his office was forced open. It was Severus Snape looking a bit uneasy.
"Severus, are you all right?" Dumbledore asked.
Severus pulled up his sleeve to reveal a dark mark burning black.
"It happened just a few minutes ago with out warning." Snape managed to say.
"Severus, I believe you should answer it. I will alert the old crowd of this development after I make sure young Harry and the Weasleys who I believe Harry is visiting for the summer are in a safe location." Dumbledore replied, staying calm as usual.
Snape left Dumbledore's office while Dumbledore went to go locate the Weasleys...