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 twin brother of Charles di Britannia, but has become immortal at an early age showing an seemingly immense age difference. C.C. refers to V.V. as Charles' first ally and has indeed been actively supporting him in his childhood years. He also seems to have known Lelouch Vi Britannia's mother Marianne Vi Britannia and C.C. In exchange for his Geass, Charles agreed to destroy "The Gods".

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 Though 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 urising. 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.

It was eventually revealed that he is the one that killed Marianne, believing that Marianne had changed Charles too much. In order to protect Nunnally, Charles ended up using his own Geass to rewrite the memories of all those involve, making Nunnally the witness, as well as making her close her eyes, while also makes it seems like a terrorist attack.