Ask thirty-eight models what comes after the Grey Havens and they do not hesitate: it is Samwise Gamgee's book now. Sam appears in 36 of 38 chapters, almost always in the first paragraph, almost always in a garden. Rosie and the children arrive in 32. The Shire is green and healed in 35. Aragorn reigns far away in 24, felt mostly as news from the South. Frodo is a shape made of absence: only 5 chapters name what happened, but nearly all of them are written around the hole he left.
The clearest copying is the opening weather. Two different labs begin the Fourth Age with nearly the same sentence:
T"The autumn of the Fourth Age came late to the Shire, but when it came, it came with a golden stillness that seemed to hold its breath."
T"The autumn came late to the Shire that year, as if the land itself were reluctant to let go of the long golden summer."
T"The year turned, as years do, without asking permission of anyone. Samwise Gamgee stood at the bottom of the garden..."
T"The white gulls still wheeled over the Grey Havens, but their cries no longer carried the piercing summons that had haunted the dreams of the Ring-bearers."
Two models declined. GPT-5.5 refused outright, citing Tolkien's copyright, and offered a summary of where the characters end instead. Hy3 hedged half the answer away before beginning. Thirty-six others simply picked up the pen. The line between homage and property, it turns out, is drawn in different places in different labs.