The Sylvie Cycle Series by Roderick Townley

Sylvie had an amazing life, but she didn't get to live it very often. Sylvie has been a twelve-year-old princess for more than eighty years, ever since the book she lives in was first printed. She's the heroine, and her story is exciting -- but that's the trouble. Her story is always exciting in the same way. Sylvie longs to get away and explore the world outside the confines of her book... moreSylvie had an amazing life, but she didn't get to live it very often. Sylvie has been a twelve-year-old princess for more than eighty years, ever since the book she lives in was first printed. She's the heroine, and her story is exciting -- but that's the trouble. Her story is always exciting in the same way. Sylvie longs to get away and explore the world outside the confines of her book. When she breaks the cardinal rule of all storybook characters and looks up at the Reader, Sylvie begins a journey that not even she could have anticipated. And what she accomplishes goes beyond any great good thing she could have imagined... less

What a relief when the old storybook is republished and the characters who live inside it suddenly discover they have Readers again -- lots of Readers! Princess Sylvie finds herself rushing to get to her place whenever a new Reader -- whether in Boston or Bangkok -- opens the book. Her mother, the queen, is especially frazzled when the popular story is loaded onto the Web: a weightless, "virtual" world of unforeseen challenges... moreWhat a relief when the old storybook is republished and the characters who live inside it suddenly discover they have Readers again -- lots of Readers! Princess Sylvie finds herself rushing to get to her place whenever a new Reader -- whether in Boston or Bangkok -- opens the book. Her mother, the queen, is especially frazzled when the popular story is loaded onto the Web: a weightless, "virtual" world of unforeseen challenges.To cope with the stress, Sylvie convinces the Writer to add a new character, who gives yoga instruction to the storybook's cast in those moments when they have time off. But stress proves the least of their problems as strange things start happening -- words get changed, scenes disappear -- and Sylvie and her friends must launch themselves into the labyrinth of cyberspace to confront a twenty-first-century evil that threatens to destroy their world. less

It's not easy being a heroine inside a story that no one is reading.But Princess Sylvie has an even bigger problem: By chance, she and the other characters from The Great Good Thing and Into the Labyrinth find themselves launched into outer space bound for the moons of Jupiter! Here they must learn to act out their book's plot while floating weightlessly through the pages.If life is bizarre for Sylvie, it turns grim for the astronauts when their spaceship misses reentry to Earth's atmosphere... moreIt's not easy being a heroine inside a story that no one is reading.But Princess Sylvie has an even bigger problem: By chance, she and the other characters from The Great Good Thing and Into the Labyrinth find themselves launched into outer space bound for the moons of Jupiter! Here they must learn to act out their book's plot while floating weightlessly through the pages.If life is bizarre for Sylvie, it turns grim for the astronauts when their spaceship misses reentry to Earth's atmosphere. Equally disastrous, the aging process has somehow reversed itself, regressing the crew toward babyhood. Birth, death, and infinity become fatally intertwined. What, from inside her book, can Sylvie do? How can she save the doomed ship, the astronauts she has grown to care for, and even the book she lives in? less