Lelouch Lamperouge in First Season

Lelouch is introduced in the first episode of the series as a student of Ashford Academy, where he is a member of its student council. A brilliant thinker who is quite talented at chess, he lives with his younger sister, Nunnally, and their maid, Sayoko Shinozaki, at a house situated within the compounds of Ashford Academy, where they are looked after by the Ashford family.

Lelouch accidentally boards a truck being used by Japanese resistance operatives. Within the truck is a capsule holding C.C., who sacrifices herself to save him from the military forces trying to recapture her. When it seems as if her sacrifice was pointless, C.C. suddenly touches his hand and offers him the "Power of the King", the mythical power of Geass. The Geass manifests itself in him as the power of absolute obedience, which allows him to make people obey his orders without question. He uses this power to order the Britannian soldiers to kill themselves.

With his new power, Lelouch begins his rebellion against the Empire, starting by killing his half-brother, Clovis, after extracting information about the murder of his mother, Marianne. He later forms the Order of the Black Knights and takes up the identity of Zero to lead them, becoming a revolutionary and gaining popular support amongst the people.

The turning point in his rebellion comes when Euphemia li Britannia declares the region under Mount Fuji the Special Administrative Zone of Japan, giving the Japanese people their name and country back, albeit in a much smaller area. This effectively destroys any possibility of the Black Knights' rebellion; acceptance would render them powerless and refusal would make them pariahs. Lelouch confronts her at the opening ceremony and tries to have her shoot him, hoping to make himself a martyr. When she says she plans to give up her royal title, he surrenders and agrees to work with her. However, at this moment his Geass permanently activates without him knowing, and an offhand comment about ordering her to kill the Japanese causes Euphemia to do just that. Lelouch reluctantly kills her and uses the massacre as an excuse to spark the Black Rebellion, in which he declares Japan to be an independent nation and leads an attack on the Tokyo Settlement. The attack goes well at first, but when Lelouch learns that Nunnally has been kidnapped, he abandons the battle, leaving his forces helpless against the better-organized Britannian military.

Lelouch makes his way to Kaminejima to search for Nunnally but is confronted by Suzaku. Suzaku exposes Zero as Lelouch to Kallen as she attempts to protect him. Lelouch attempts to broker a truce for Nunnally's sake, but Suzaku is distraught over the death of Euphemia and refuses to listen.Lelouch draws his pistol and both he and Suzaku attempt to shoot one another.