It’s a bit of a thriller/adventure type, but not a superficial plot. Not sci-fi, but takes place in the future in a society that is centuries post-apocalyptic. Not fantasy, but is a world different from ours, or at least our world is forgotten from theirs. Main character is a young man/teen who was orphaned when his (royal) family was conquered by another government. He vows revenge against his new government, but unexpectedly becomes of a part of its high society through his cleverness and strength. Very appropriate for any age without being a kids book, although there is fighting. Great read.