First and foremost, starting is Elrond specifically because the lord of Rivendell is a far different character in The Hobbit than he is in Lord Of The Rings. Less solemn and brooding, he conveys a sense of merriment and wisdom when Thorin's company meet him. The elves in the book play music, they since and dance and Elrond sits at the head of it all. There is not yet the weary sense of a world ending that the elves - and Elrond - have when they meet Frodo Baggins many years later. It was important that this be captured in the adaptation of The Hobbit and An Unexpected Journey did this beautifully. There was still the Elrond familiar to us in the scenes with the White Council and Thorin's map but we saw a livelier, friendly side too. The elves may not have been quite so whimsical as they were in the Hobbit, but there was still mirth and merriment aplenty to serve as an emotional break between the trolls, orc pursuit and the events in the Misty Mountains. It is logical to assume that Elrond will appear again in The Battle Of Five Armies, either at the titular battle itself or - like the events of the book - during Bilbo's journey home. Either way, there will be a sure chance to visit Rivendell one last time before the journey to Middle Earth is complete. Let's hope it remains a happy one.