Disclaimer: I don't own Code: Lyoko or .Hack/SIGN.
Lord Maximus: This has nothing to do with my other crossovers, but I will be using Xana's form from them. It is much easier than thinking of a new one.
Summary: Xana has finally been destroyed, but is it the end? No, it has only begun. Another virtual being has taken over Lyoko ad plans to take over the world. A group of warriors from another virtual world comes to help the Lyoko gang, but will that be enough?
During the year 2005 a powerful virus named Pluto's Kiss nearly crashed the entire internet on December 24. All networks and communications were shut down because of that. 77 minutes later the entire was able to recover from the incident and it was discovered that the one who created Pluto's Kiss by a ten year old elementary student, whose name is unknown whether he/she escaped. From that incident a virtual game called The World.
A player named Tsukasa was trapped in the world after a horrible accident. His human mind was trapped in The World and his body was put into a coma. It was discovered that Tsukasa had discovered a girl named Aura who was created the creator of the World himself. He was disappointed he failed as a father in real life and created an AI named Morganna to watch over Aura, but Morganna went rogue.
Tsukasa made many friends who helped rescue Aura before she became negative and defeated Morganna. The corporation of The World assured everyone that Morganna's code would be entirely defragmented so she could never return. However Morganna is defeated so easily. She has hidden herself deep in the World to avoid deletion.
At the same time, Franz Hopper, a close friend of Harold suffered the same disaster as his daughter Aelita died in a car accident. He used the technology that created the World and made Lyoko where Aelita was reborn as an AI. He created a guardian for Aelita named Xanadu. He was an AI who protected Aelita from falling into the digital void and helped her learn about the worlds.
However Franz Hopper's life had just turned worse. The authorities came to the factory to shut down Lyoko and take away the technology. Franz would let them do it easily. His wife perished after Aelita died and he could not bear to lose his daughter again. Aelita and Xanadu overheard the fight and watched through the cameras.
Aelita was sobbing as she watched her father being pummeled by the cops as he tried to protect his daughter. Xanadu watched her as she cried and went into the depths of Lyoko where he discovered Carthage. Inside resided a powerful virus that was trapped in it. It told Xanadu that it could help Aelita for a price.
Xanadu agreed and sold his body to the virus as it entered his system. This led to the birth of Xana. As his first act Xana tested his new power by activating a tower, which was like folder for information, but Xana used it to hack into the technology of the factory.
A black cloud emerged from the computer and entered the machines.
"You are under arrest for use of illegal technology." said a cop,
"I will not let you take my daughter!" shouted Franz.
Suddenly the machines came to life as the cops turned and saw. The machines moved and attacked. The cops either tried to run or defend themselves, but the machines, like animals did not allow their prey to escape. They slaughtered the cops one by one.
Aelita watched and knew it was her guardian. She sensed him in Lyoko and discovered that he had a new, different aura. It was dark and pure evil emanating from him. She ran out of the tower and saw a black cloud waiting for her.
She knew who it was.
"Xanadu, why have you killed them? Our creator, our father is dead. Along with others." said Aelita,
"It is my duty to protect you and Lyoko and those humans sought to destroy you. I only did my duty. As for my name it is no longer Xanadu. I am now known as Xana." said the cloud.
The cloud glowed with a red symbol that looked like an unbliking eye. A sea of black clouds came, taking of forms of metallic monsters. Aelita ran as the monsters came for her and sent an S.O.S. out onto the internet. Not too far away at a boarding school, a boy named Jeremy Belpois recieved it and his friends discvoered Lyoko.
That is where our story begins.