Queen of Babylon
(Book)

"Thirteen-year-old Josephine has always seen herself as a loner, not a hero. She survived the end of the world--and what came after--by talking to her twin's ghost in a secret language they call the Twinkling. Transformed into a biomechanical robot, she's been charged with protecting the Bay Area--now Yerba City--alongside an army of her clones called the Josephines. But when Yerba City is threatened by a devastating language virus, the Twinkling is the only thing that stands between the last shreds of civilization and the Babble." --,(Source of summary not specified)