There was this book series with three kids from three different planets/universes. One of the kids has blue skin and I think they end up meeting their future selves as the rulers of a planet they all meet up at. Anyone know this book series?
This is the Diadem series by John Peel.
The Diadem is a network of worlds, each tied in eternal circuits around the central core of magic. So long as the Triad is in control of the center, magic and the worlds are secure. But lately things have started to come undone. Someone must go the the center of the Diadem and set the worlds right again.
Score is a street-tough punk from New York City. Product of a broken home and an abusive crime-boss father called Bad Tony, Score has little to look forward to but a life and early death in the back alleys and underworld of the city.
Pixel comes from a world where The Matrix is the reality. The only human contact he knows is in Virtual Reality. He has never even been outside his house, and his parents are distant memories.
Helaine is the child of a lord in a medieval-style world. Using the name Renald, she disguised herself and learned to fight with the best of the knights, but to her father she is nothing but a pawn in the game of politics.
All three are plagued by vivid dreams of a book and a jewel. Soon, each are pulled from their worlds by powers and magics beyond their control.
They have been selected for a dangerous quest, one on which all worlds depend.