Fanon / Code Geass

• Half of the fandom believes that Lelouch became the now-immortal Code-and-Geass-wielding R.R. (Japanese R = L) who lives happily ever with C.C. a la Spice and Wolf's Lawrence and Horo (Lelouch and Lawrence do have the same seiyuu after all), as allegedly shown or implied in the "Cart-End" final episode. This mainly due to the fact during and after Lelouch's attack, C.C.'s mark is always covered by her hair, and thus unknown if it is gone or not. As it turns out in the CodeGeass picture drama set after the end of R2, he's dead.
• Fans also love to justify Kallen's Spell My Name With An S by claiming she goes by "Karen" when acting as a Japanese and doing Black Knight stuff, with her birth name being supposedly "Kozuki Karen", and by the most westernized "Kallen" when in public as an Eleven, as part of the "Kallen Stadtfeld" identity. None of this reflects on canonicity, though.
• Rolo looks like a male version of Nunnally and has an eye color that only members of the royal family have. This has led many fans to speculate that he's either Nunnally's long-lost Half Identical Twin, her illegitimate half-brother or any other sort of relative.
• The origin of Lelouch and Nunnally's false surname, Lamperouge; more often than not, it's believed to be their mother Marianne's maiden name, but there's been precious little information about Marianne before she married Emperor Charles.^note There was a short Light Novel detailing an attempted coup in the 1990s, but it only ever refers to Marianne by her first name
• It's common among fans to assume that Marianne has French ancestry due to her name. Again, nothing about it is revealed.
• Many fans assume that Milly Asford was more aware of events going on then shown. They generally suggest that she was at least aware that Lelouch was Zero, or suspect he was connected to him somehow, due to knowing him for so long.
• Due to material from the light lovels, his appearance (and death) at Narita, and the presence of Code R in the same location, many fans believe Joseph Fenette was connected to Code R. Shirley is rarely, if ever, told this.....for her own good.
• Fans are also fond of referring to the first season as "R1", since the second was called R2 and they seem to assume the R stands for "Round" or something similar (this also extends to calling Lelouch of the Resurrection "R3" for short). Officially the first season was only ever referred to by its full title or simply "Code Geass Season 1", while Word of God said that "R2" stood for Return and Revolution, the two things Lelouch accomplished over the course of the season.
• Being a Code bearer is a Death-Activated Superpower. This usually goes hand-in-hand with the theory that Lelouch became immortal at the end of the series.
• Fanon will often suggest that V.V. was responsible for Lelouch's geass acting up and the resulting "Euphinator" incident. While he definitely made the aftermath worse, there is no clear evidence that V.V had anything to do with the events that occurred at that point, even if it is not hard to imagine V.V doing so.
• One with regional divides: while in eastern fanbases such as China and Japan the Britannian Imperial Family usually doesn't get larger than it is shown to be in canon (with non-children of Charles in the succession to fill the number out), the fanbase in the west will typically have Charles with many more children than the show or side material shows to make the entire succession line between Odysseus and Nunnally filled with his children. This naturally leads to a lot of original characters created to fill the family tree.