If it goes like they say it goes, the cycle remains unbroken: each Doumeki son and daughter comes to the shop and follows as their patriarch did, all those decades ago. The trauma reverberates down the generations, every child knowing that their existence is a sacrifice their parents (grandparents, great-grandparents) made to keep Watanuki in this world. Every child knows that they come from a family born out of pain. Sayaka comes to Watanuki’s door (Yuuko’s door), holding the egg, and his great-grandfather whispers to him that the time has yet to come.
If it goes like a dream, then Watanuki passes into oblivion, slowly unmoored from the world until no Doumeki or Kunogi or Tsuyuri remembers him. Only Syaoran keeps him, travelling from world to world, and even then, Watanuki appears fainter and fainter, further and further. When Sakura dreams of him, she sees only a ghost. No one remembers the sound of his voice, or the taste of his food. Watanuki drifts out onto a dark ocean until he forgets he ever knew the shore.
If Doumeki and Kohane live long enough and die well enough, then the Seretei welcomes them, and the Tsuyuri-Doumeki Clan becomes a name the shinigami do business with in fear, in awe. The Doumeki children all come to the shop, eventually, and when they all die, eventually, they all come to the doors of the clan manor, ready for war. They shoot bows drawn from the air and bolts of fierce light, they tell fortunes and pull fate’s red strings as it pleases them. Some of them pledge their sword to Watanuki, and he learns what it is to be a liege as well as Shopkeeper. All of them appear terrible and bright, as apocalypse after apocalypse threatens the worlds, in rippling robes with the sigils of their clan gleaming on their chests. (In this world, the sigil is a hawk and a peony. Watanuki loses their loyalty when they die. The Clan is all-consuming.)
If Doumeki tells Watanuki good-bye, and means it, then the ghost of Yuuko, if it exists, is proud. Kohane will never marry, with no wish for a spouse and no wish for children, and she will burn incense on her little altar as if Watanuki had died at eighteen. Watanuki will not understand the choice. Watanuki will not understand that he has chosen a world Doumeki will not follow him into; he will not understand that this wound is of his own making. He will have never learned the lesson of the spider and the eye, from all those decades ago.
If Doumeki stays, then Watanuki will also have never learned the lesson of the spider and the eye. If Doumeki stays and turns his back on the world he was born to, then Watanuki and he grow into a marriage of gods. They are more powerful than Yuuko ever was, the sight and the bow united, and all worlds tremble where they walk. Watanuki grows into something coolly gracious and coolly cruel. Doumeki follows him unto the ends of the worlds. The dead will rise, chattering, and the two of them will dance in each other’s arms to the sound of the bones.