Doppels or rather doppelgangers, are holographic robots in the futuristic world in which Fractale is set. In the beginning of the series, Clain lives with doppels that are representations of his parents.
They are essentially puppets controlled remotely by someone to allow them to experience different locations, both real and imaginary.
It has been seen throughout the series that Doppels, do not have to look like their original counterpart. Seen with Clain's own parents.