Another of my recent “buy a bag for $10” purchases from the local library. The Grey King is part of a multiple award winning series of YA fantasy books set in Wales. The series is composed of two separate story-lines. In one a bunch of siblings and their uncle Merry have a series of adventures, in the other Will discovers he’s the last of the “Old Ones” and is mentored by a wizard named Merriman. The Grey King is the last of the “Will” stories before the series merge together into the final book with all the players together at last.
Read the whole series from the beginning, of course.