The manga is the canon story. Period. The anime is made out of the manga. The Clamp added scenes that didn't exist.
Also, Lelouch is playing Chess. Not killing Kallen is the best thing he could do. She's too helpful to just kill her off. Also, when the story advances he gets closer to her and cares for her, but that doesn't mean he's in love.
Those where alternate story lines plus the Anime was made before the manga. So how is the anime adapting the manga if the anime was before it? Only other way is if someone from the show said different. Explain this to me.
Edited by DeathGodMack, 23 December 2015 - 08:27 AM.