Ar

Ar (アル, Aru) is the protagonist of Code Geass: Genesic Re;Code. His real name is Arpirica Hueden (アルピリカ・ヒューエデン, Arupirika Hyūeden)

Geass
Ar's Geass is the power of Phase Transition, manifesting in his left eye. Using this Geass, it allows him to observe events in history. While using this power, he is not aware of himself, and watches events unfold in a manner he compares to watching a movie.

Perhaps due to the nature of Fimbulwinter, while using his Geass, he vanishes from wherever he is, and reappears once his observation has ended in the ruins area.