The Search for WondLa Series by Tony DiTerlizzi

Eva Nine is a curious and sensitive twelve-year-old who has existed only in a subterranean home called Sanctuary, cared for by a robot named Muthr. Eva's great desire is to go aboveground, and her wish comes true, though not as she had imagined. On the surface, Eva goes in search of other humans--she has never met one--and soon meets both friend and foe.

Eva Nine has finally found what she has always been looking for; other human beings. Having been rescued by Hailey, Eva couldn't be happier, and now Hailey is taking Eva and her friends to the human colony New Attica, where humans of all shapes and sizes live in apparent peace and harmony. But all is not as idyllic as it seems.

All hope for a peaceful coexistence between humankind and aliens seems lost in the third installment of the WondLa trilogy. Eva Nine has gone into hiding for fear of luring the wicked Loroc to her companions. However, news of the city Solas being captured by the human leader, Cadmus Pryde, forces Eva into action once again. With help from an unlikely ally, Eva tries to thwart Loroc’s ultimate plan for both mankind and the alien life on Orbona.