Villetta Nu is a silver-haired, dark-skinned member of the Britannian Army. Is was a member of the Purebloods who sought higher status, but fell in love and married Kaname Ohgi.
Villetta Nu is an elite pilot working under Jeremiah Gottwald in hopes of earning herself entrance into the nobility. Unfortunately she is one of the earliest victims of Lelouch's Geass, which he uses to make her give him her Knightmare Frame. She is therefore one of the earliest people to get suspicious about Lelouch's abilities when Jeremiah suffers a similar memory loss to hers. After Jeremiah supposedly dies, she attempts to discover the connection between Zero and Lelouch via Lelouch's friend Shirley Fenette, only to to have Shirley shoot her to protect Lelouch.
Villetta survives, thanks to the help of Kaname Ougi, who takes her in and protects her-- meanwhile, she has amnesia and no longer remembers who she is. During this time Villetta and Ougi fall in love, and when Villetta regains her memory she struggles with her feelings.
By the second season Villetta has entered the Britannian nobility thanks to her knowledge of Lelouch, and she is posing as the P.E. teacher at his school in order to keep an eye on him. When Lelouch recovers his own memories, he blackmails Villetta with her love affair with Ougi and uses her to escape from the watch of Britannian Intelligence. When the Black Knights come to believe that Zero has betrayed them, Villetta ends up joining them to fight against him, and eventually becomes pregnant with Ougi's baby. At the end of everything, she and Ougi are able to marry.
When working for Britannia, Villetta is determined, focused, and skilled. During her time as an amnesiac she is sweet, kind, innocent, and vaguely sad when she thinks about the past life she can't remember.