The Emperor of Nijon-Ja by John Flanagan

This is the tenth book in John Flanagan's wonderful Ranger's Apprentice series. A ranger is defined as a warrior who is more stealthy than a knight, one who blends into the forest and attacks by surprise. They move without noise. They are expert archers with a longbow, and they use a short saxe knife instead of a sword. They do not have the status of a knight, but they are well respected. The first four books in the series show Will, who is the ranger apprentice to Halt (perhaps the greatest ranger of all time), learning his trade. He shows bravery, but also inexperience. He gets himself into some very difficult situations where it is not at all clear that he will emerge intact.
Will grows into a fine Ranger, and along the way he forms a romantic relationship with a courier (Alyss), a strong friendship with a knight (Horace), and an almost sibling like relationship with the princess (Evelyn). This band forms a sort of family with Will's mentor, halt at the lead. In subsequent books they form various alliances with local groups, and bring on a magical herbalist (a Merlin like character) to expand their options, but they are the good guys who take on all sorts of bad guys, one book at a time. Now that there are ten in the series it is a perfect set to give to a child who likes to read a group of related books.