After rooting for Will through every high and low on his journey, we get to see him defeat the Dark. Okay, we actually get to see the Hunter do it, but that's just fine with us since Will's only eleven—we think physically fighting off evil is maybe best reserved for someone a little older. After the Hunter is victorious, Will meets up with the other Old Ones for a good, old-fashioned celebration. Sounds awesome, right? But then we get hit with this:
The road was empty; no one was anywhere to be seen among the trees. Will could have wept with the sense of loss; all that warm crowd of friends, the brightness and light and celebration, and the Lady. (13.46)
Oh, poor Will—he's upset about being done with his quest. It was harrowing and taxing and world-upturning, but he enjoyed it nonetheless, and came to really love the Old Ones. At the very end then, Will suddenly realizes that he has nothing else to do except go home, and that bums him out (for more on why, swing by the "Setting" section). He loved working with Merriman and saving the world, one Sign at a time.
If you're feeling bummed, too, though, worry not—Cooper is totally setting us up for the sequel by ending on this note. After so much hard work, Will deserves a happy ending… and since he doesn't quite get it yet, we know this isn't the true ending to his story.