V.V.

V.V. (ヴイ・ツー, Vui Tsū can be pronounced V2) is an ally of the Britannia, most often seen accompanying  the Charles Di Britannia and gave him his Geass. He is known to have given several individuals in the Empire (including Rolo) the power of Geass. As with C.C, he is virtually immortal, both unable to be harmed with physical damage and as well as age, appearing as a young boy throughout the show.

Overview
He is the older twin brother of Charles di Britannia, but as has become immortal at the early age of 10, there is an seemingly immense age difference between them. C.C. refers to V.V. as Charles' first ally and has indeed been actively supporting him in his childhood years. Charles and V.V. childhood years were marred by an internal feud in the Imperial Family called the Emblem of Blood. This period filled with deception and assassination resulting in the deaths of various members of the royal court including their mother. This event made convinced the two to create a Geass contract to create a world without lies and to do so, they intended to destroy the "Gods". Several years later, Marianne Vi Britannia and C.C. joined their venture as well.

First season
During the time of both the invasion and Black Rebellion, V.V remained behind the scenes hiding among the highest ranks of the Britannian Royal Family. He and Charles were starting expeditions to find Thought Elevators across the planet. His first known appearance was revealing himself to Suzaku Kururugi a few hours before the Black Knights began their rebellion. Revealing to him that Zero was responsible for Euphemia Li Britannia's murder. After that he kidnapped Nunnally Vi Britannia and once again disappeared into the Sword of Akasha using a thought elevator, resulting in Lelouch's sudden abandonment of the Black Knights' chain of command.

Second season
V.V was more active during the Black Knights' second uprising. He leads the Geass Directorate, a secret organization that studies and produces Geass users, as with Jeremiah Gottwald's Geass Canceler. However the research would stop as the Black Knights invaded the Order killing all the researchers, civilians, and subjects, as well eliminating all traces of their research. In the ensuing chaos, he pilots the Siegfried during Lelouch's assault on the Geass Directorate. Though he manages to hold his own at first, he is caught off-guard by Cornelia, who has hotwired a damaged Akatsuki with an array of weapons. She and Lelouch destroy the Siegfried together. He manages to reach the Twilight Door in the complex and give his immortality to his brother, then succumbs to his wounds.

In a flashback, it is revealed that V.V. was the one who assassinated Marianne, having done so out of jealousy. He lies about this to Charles, betraying the pact they made which was to never lie to each other.