He knows what it is to believe, does Shepherd Book; to believe with all your being that perfection is knowable, understandable, and attainable, that taking but one road will get you there and that even one detour, no matter how small or seemingly inconsequential, has the power to bar that way to you forever.

There was a time when he would have looked upon Malcolm Reynolds and the crew of Serenity – indeed, upon the ship herself – just as motes upon that perfection that needed nothing more than to be polished out.

But a lot of time has passed since then, time in which the Shepherd himself has suffered the rough side of the cloth at times. And though his faith remains strong, he has taken to his heart some strong doubt, as well, and it is this he now lets guide him.

When he boarded the ship that morning from Persephone he had no doubt he was heading into darkness, away from the light, away from his own, lost, perfection and, hopefully, toward the possibility of it in others. But he is confident that this path is now his: he had seen a sign, and that sign had said ‘Detour’.