Sitting bored at work, and been thinking about how the greatest defeat to Bill would be that he should be completely forgotten.
He sits in his own purgatory in theraprism, and years go by, the Pines change and live past Bill, and when it comes to a point that the last Pines passes that has knowledge of him, the axolotl releases him.
And a new set Pines of twins are born, named for uncles that had "cool names" a few hundred years before. Bill is born again parallel to them, and when the men have grown again, Bill confronts them, appearing insane, cursing them from another lifetime of woe, and attempts to destroy them, and once again is committed.
He is a relic from another time and place, and the very thought of two reincarnations of his mortal enemies looking at him and going: "I don't even know you." plainly causes his brain to snap, in which he tries to then commit to killing them, and is once again sent to another version of theraprism. He is the only one who remembers what he was.
Save for the axolotl who knows this is a torture worse than any other to Bill, and continues to let the demon rot in the cycle of hell.