SOLVED. YA fantasy series, boy stuck in labyrinth and princess outside of it. [s]

[Isabelle]

I read this book around 2011-2013 though I think it may have been written a couple years before then. It was young adult fantasy I think. The story switched between the perspectives of a teenage boy who lived inside a dangerous labyrinth with things like monsters and rooms that constantly changed that he and his friends spend the novels trying to escape, and a teenaged princess who did not live in the labyrinth. A big part of the story was understanding where the labyrinth was and I believe the big twist was that the labyrinth was a small cube in the princess' world that people like the boy were trapped in. At some point they became aware of each other's existence and the girl began to look for the key/a way to open up the labyrinth and free the people inside of it. In truth my memory is very fuzzy on specific details, but I think the plot is decently unique?? I haven't read anything like it since then. But I do 100% know it was about the labyrinth and the people trapped on the inside, while the princess was on the outside. The physical books (I remember there being two that I had) had intricate silver design all over the cover with a key on the front in the middle. One was dark green and one dark blue. I also know that they were both one word titles.

[Spockles]

and by Catherine Fisher

[Isabelle]

Spockles wrote: " and by Catherine Fisher"

That's the series, thank you!! Now to see if I actually remembered anything correctly lol.