This was maybe 6 or so years ago. It was a physical book, written in English. I don’t remember anything about the cover.
The book takes place in a fantasy medieval setting. There were two siblings in the book. In the beginning of the book, they lived with an abusive couple (I think they were adopted). One day a member of the family that lived somewhat nearby flew over by dragon and took the children. I don’t remember why. The family tried to get them to join it. At some point, they give the brother a fancy watch to get him to be loyal. The sister takes care of an old female dragon (I think it is revealed later that the dragon hates the family and betrays them somehow).
There is also a girl that lives in a setting that’s essentially “real Earth” (modern Earth, that is). Her mom is in the hospital or is sick, I’m pretty sure. Her mom told her stories about dragons, and the girl believes they exist. She gets threatened by some girls with knives (I think three) twice in the story for money. I think she knew them personally. The second time, she is saved by the siblings mentioned above on a silver dragon (silver dragons are special somehow) after somehow finding their way to that world.
I don’t remember for sure, but I don’t think the story was concluded with that book (i.e there may have been more books in the series).
Probably one of the biggest ID factors is that there was a card game that came with the book, based off of the book. The rules for the game were in the back of the book.
