Chapter 3 - Aelita's Rebellion
Because Aelita was Xana's servant in Lyoko, Xana gave Aelita full access to the towers such that to maintain them in his absence. Xana had also given Aelita other special powers within the towers, including the ability to reprogram Lyoko and transport to different parts of it. At this point, Aelita was getting tired of working for Xana. Because Aelita was created the same way Xana was, she was also gifted with a mind of her own. He knew what Xana was doing was Xana was evil. Therefore after Xana had finished reprogramming Aelita, Aelita began her rebellion. She told him that she refused to help him destroy humanity.
Xana was furious of course. This turn of events caused Xana to hold off on his plans of the destruction of humanity, so that he could deal with his buggy servant first. He was starting to regret giving Aelita all the power he did. In order to stop her, Xana created a series of monsters and stationed them throughout Lyoko. The only thing Aelita could do in order to elude Xana's monsters is reprogram Lyoko to her advantage, and run, hiding in towers. With Aelita no longer a threat, Xana could pursue his original plans.
He first started to test his plan, to make sure it was successful. His plans first started by activating one of his towers. With the power from the tower, Xana would be able to hack into a computer system. The first test of his plans consisted of hacking into the computer mainframe of a nearby boarding school called Kadics Junior High. In the school, all computers connected to the mainframe, stopped what they were doing entirely. They then all displayed a target symbol with four lines sticking out of it. Xana was impressed with himself and concluded this test was a full success. But Aelita knew what Xana was doing. In order to stop him, she followed pulsations in the ground until she reached the activated tower. She then entered the activated tower, climbed to the upper tier, and then deactivated the tower from the inside. Time then reversed itself in the real world to about 24 hours before Xana activated his tower. From this point forward Xana knew he had to protect his towers with his monsters in order to prevent Aelita from deactivating them.