[Galadriel55]

Very interesting thread, and very interesting ideas!

As I was reading this thread, it occurred to me that an additional difference between Bilbo's and Frodo's returns is their feeling of responsibility. Bilbo never felt responsible for the world, or for the Shire more specifically. Meanwhile, Frodo knows full well the gravity of his mission - it's not just adventure for him - and it weighs down on him, especially because he transposes that sense of responsibility onto his home. He goes through the entire journey in part to save the Shire, to keep it whole.

Of course, that's a perilous path to take just on its own. If your beacon of light is your memory of a person or place, coming back to realize that it (or you) changed in your absence and there's no going back to the way it was before is harsh. But in Frodo's case, there's the added sense of responsibility. He felt it was his duty to keep the Shire safe and hobbitishly unconcerned about the greater troubles of the world. He came back to find that he failed on that count, and he failed to keep the Shire from "growing up" character-wise (becoming worldly-wise?) even when all the repairs were finished. In a way, the Shire as a whole developed during that year like Bilbo during his trip. The Shire changed too, not just Frodo.

New thoughts are popping into my head, and I realize I'm falling a bit off my original track with them. The thought I wanted to put out is that Frodo feels responsible (and guilty) for the change that happened in the Shire both physically and character-wise. Bilbo doesn't feel the responsibility for the Shire, and it doesn't change much during his journey; it's only him that changes. He just looks at the same Shire with different eyes - the things that used to matter to him stop mattering so much. But for Frodo, the biggest pain is that he wants to go back to the memory of his peaceful life before the Ring, filled with small earthly concerns, and he can't. So The Hobbit ends up bitter-sweet, but positive, slightly "grown up", but LOTR ends up sad and nostalgic.