Do you have an aversion to reading children's fiction at all? A lot of it is very well written and easily stands against adult fare.
In no particular order.
The
Alex Rider books by Anthony Horowitz - Teenage boy recruited as a spy. However, the books always make it very clear that being a spy isn't all excitement and gadgets but is all too often misery and fear. Alex is very much the reluctant hero and some of the more recent events are truly horrifying. First in the series is Stormbreaker.
The Edge Chronicles by Paul Stewart and Chris Riddell - High fantasy but not swords and sorcery stuff. They have written a world that is outlandish but internally consistent. The lead characters don't always get a properly happy ending either. Also the books are beautifully illustrated without with maps, scenes and characters from the stories. The books come in trilogies. The earliest chronologically is The Curse of the Gloamglozer.
Varjak Paw by S F Said - Story of a young Mesopotamian Blue cat who leaves the only home he has ever known to try to find a way to protect his family. Has some quite tough sections and I'm pretty sure a nasty surprise is coming up (I'm on page 208 of 254 at the moment)
Skulduggery Pleasant by Derek Landy - Skulduggery Pleasant is a detective, but a slightly unusual one. He's an undead skeleton solving mysteries in a fantasy world that operates alongside our own more mundane reality. High action adventure but written with a lot of wit and style and some truly classic bits of dialogue. I liked it so much that I got the sequel and read all 300+ pages in less than a day and a half.
