Fantasy series. Boy learns secret about his mother & travels to another realm. Read 2007-2015 in German. Spoiler.

[Linda]

SPOILER WARNING

I do not remember much abt this book except that the protagonist is a boy who learns that his mother is/was the long lost queen if some fantasy parallel universe.
I also vaguely remember there being a dragon burning could be totally wrong abt that.
I'm also pretty sure that it was, a book series. I read it between 2007 and 2015 in German. It didnt seem to be very old but I could be wrong abt that.

[Kris]

Linda, is this fantasy series for kids or teens? How old is the boy?
Where does he live on Earth?

I copied a few book details to the topic header. Feel free to edit it.

[Kris]

The Secret Country: Book I by Jane Johnson?

Google Book preview: https://books.google.com/books?id=wgx...
There are different cover images.

Google search of Goodreads:
site:goodreads.com "fantasy" "secret" "his mother" "long lost queen"