SOLVED. Children's/MG Fantasy involving multiple universes and "circles" of magic. [s]

[Molly]

I read this book in elementary school probably between the years of 2000-2005. It was probably published in the early 2000s or late 90s.

The basic premise was that there were various different universes/worlds that were like layers around a magic core, and the closer you got to the core the more magic you could use.

The main characters were two boys and one girl. The first boy was from our world, the second was from a very sci-fi, futuristic type world, and the girl was from a vaguely medieval-fantasy world. While I don't remember a lot about the plot, I do remember that there was a lot of fuss over not telling anyone your full name, to avoid giving them power over you.

[Michele]

Molly, do you remember if the book was new at the time you read it, or an older book? Can you recall anything about the cover? How old were the characters? Do you remember how they traveled through the layers?

[Cupcakedoll]

This is the series, I think this is the first book but could be wrong.

[Molly]

Oh my gosh you found it! Thank you!!!