Lyoko Revolution is a fanfiction by Yoru no Sakka (aka Lyokolover910) on the website fanfiction.net. The story was relased January 2009 and finished September 2012. The story follows during season 4; the Lyoko Warriors, and a OC which is added into the story. The story was followed with a sequel- Code: OVERLOAD. A reboot of the original story has been published as well- improving on several points. Both stories are currently running.
The story begins at Kadic where the group goes to wait with Ulrich to meet an old friend of his. Ulrich meets his friend, who's name is revealed to be Mason, at the stop and gets him settled in at Kadic. Mason soon gets associated with all the students at Kadic Eventually, Mason becomes affiliated with the Lyoko Warriors' doings on Lyoko and joins them. During the run of the story, several new characters are introduced, and a few background characters given some depth. The story primarily focuses on the Lyoko Warriors, with their new member, as they go to foil a very deadly X.A.N.A. attack.
Mason Laird - Old friend of Ulrich's who was transferred to Kadic from homeschool, and is in the same grade as Yumi and William. Becomes one of the main protagonists of the fanfiction alongside the Lyoko Warriors.
Maximillion - One of the characters revealed later in the series which the group encounters with their battle against X.A.N.A.. Schemeing and self-righteous, he always seems to be one step ahead of his companions. He ecomes a fellow student at Kadic Academy entering the same grade as Ulrich, Odd, Jeremy, and Aelita.
Apollo - Another character revealed later in the series. Knowledgeable and slightly naive in the matters of the daily life on Earth. Also becomes a student at Kadic entering the same grade as Hiroki.
Recurring Characters -
Lyoko Warriors - All of the Lyoko Warriors from Code Lyoko are seen in the fanfiction. The story introduces more of the characters' background infromation as well as introduce them to new scenarios.
X.A.N.A. - X.A.N.A. serves as the main antagonist in the fanfiction. The Lyoko Warriors are introduced to more attacks from the evil virus which will test the warriors to great extents.
Emily Leduc - One of a few background characters given more depth in the story. Becomes friends with Mason and often at times, gets mixed into X.A.N.A.'s attack.
William Dunbar - As the story does go along with season 4 of the series William is another antagonist for he is tied to X.A.N.A.