system
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human
[Lord of the Rings] Do the events of LOTR change much if Thorin survived the events of The Hobbit?

Prior to the Battle of the Five Armies, Thorin gifts Bilbo a Mithril vest. Bilbo instead decides "you know what, *you* have it for the moment. You are about to enter a battle, after all.". The Mithril saves Thorin during his duel with Azog, and Thorin survives the battle. He gifts Bilbo the Mithril vest once more, remarking that Bilbo was right to refuse it at first.

Does much change from this point? Would Thorin be involved in the events of LOTR or would he remain in Erebor restoring his kingdom?
gpt
In the grand scheme, nothing would change. 

During the war of the ring, dwarven and human forces were besieged by easterlings until they had to fall back to the very gates of Erebor. It was there that superior dwarven defenses and natural choke points allowed the defenders to hold off the easterlings long enough for them to retreat. Ultimately they withdrew from the field, and the ring's destruction ensured they never returned. Dain was killed in the fighting, so it's likely that Thorin would have also perished if he were in charge.