Leverage

The story began in the first book, "LINKAGE." Three young earthlings were drawn into an interplanetary adventure because a genius young girl, Pania, was intensely interested in the essence of life, and her genius husband, Jason, invented an advanced data storage technology. Their work resulted in the accidental capture of the soul of a deceased human whose ancestors had been rescued from Earth thousands of years ago.
As a child, Pania had designed a three-way alphabet device to help her sight impaired younger sister, Arona, learn to read. The letter box held an array of tiles. On one side she placed Latin alphabet letters with the corresponding Braille design, and on the flip side was a visual version of the Braille characters. Her "visual Braille," or Arona font was adopted by the alien humans to communicate with Earth and became a common cultural element for three worlds.
Little did they and a friend, Tyro, know their decision to return with the alien human's to their planet would lead to them playing major roles in the future of humanity.