As the hobbits prepare to return to the Shire, Arwen informs Frodo that she and Aragorn will ride with them at least as far as Rohan, for the burial of King Theoden. She also tells Frodo that she has chosen to give up her immorality in order to live the remainder of her life with Aragorn. She offers Frodo her place on the ships of the elves that are sailing into the West from the Grey Havens, if he wishes it: "If your hurts grieve you still and the memory of your burden is heavy, then you may pass into the West, until all your wounds and weariness are healed."
King Aragorn and his company process to Rohan, where Theoden is buried. eomer is hailed as the new king of Rohan; he pronounces "the friendship of the Mark and of Gondor bound with a new bond," that of his sister eowyn's marriage to Faramir. Before they part, eowyn gives to Merry a special horn: "He that blows it at need shall set fear in the hearts of his enemies and joy in the hearts of his friends, and they shall hear him and come to him."
The company returns to Isengard. Treebeard tells Gandalf that Saruman is no longer there; in the Ent's judgment, Saruman could do no harm, and Treebeard was loathe to imprison any living thing for too long. Gandalf hopes that Treebeard is correct, but fears Saruman may still cause harm. Aragorn takes leave of the rest. The remaining company encounters Saruman and Wormtongue on the road home. Again, Gandalf offers Saruman a chance to join them. The defeated wizard, however, remains defiant: "All my hopes are ruined, but I would not share yours." Wormtongue, too, rejects the chance to leave Saruman. Saruman warns the hobbits, "[I]t will serve you right when you come home, if you find things less good in the Southfarthing than you would like."
The company eventually arrives in Rivendell, where they are reunited with Bilbo. Bilbo bequeaths his book to Frodo, telling him that he must write the end of the story that he began.
The promise of healing in the West for Frodo echoes, among other literary sources, the Arthurian legends. Just as King Arthur is carried away to Avalon to be healed of his grievous wounds, so will Frodo sail into the West to heal, not only the physical but also the mental and emotional wounds that the quest to destroy the Ring has inflicted upon him. Frodo's passing also further develops Tolkien's theme of passing and the transitory nature of life. Even though the characters seemed to have reached a happy-indeed, euctatastrophic-ending at this point in the book, it is the very nature of eucatastrophe that it does not last. As Tolkien explained in "On Fairy-Story," eucatastrophe is a non-permanent glimpse or hint of a more permanent "happy ending" to come.
Note the stylistic passage in which Tolkien also develops the theme of the world's passing in this chapter: he describes the travelers, who have stopped for the night, in terms highly reminiscent of the pekel-men. Like those carved, stone figures, the characters of Tolkien's tale are quickly becoming "memorials of forgotten things now lost in unpeopled lands."
The Return of the King: Novel Summary: Book VI Chapter 6