Lord Of The Rings: 10 Things You Didn't Know About The Elves
8. Arwen Wasn't The One Who Saved Frodo
Tolkien managed to give the character of Arwen a huge amount of weight, with surprisingly few words. You could count the amount of pages she's mentioned on, with your fingers... But this wouldn't do for the films. It was necessary for Jackson to flesh out her character and give her a slightly more significant role to play.
In the books, Arwen enters the story in a whimsical way. She's brought up in a conversation between Frodo and Bilbo when they meet in Rivendell; the reader is given an impression of a beautiful elven princess, who just floats around looking ethereal... It wouldn't have made for a very exciting introduction.
Jackson made the wise to decision to axe another elven character and fold his role into Arwen's. The entire chase sequence with the Ringwraiths was largely invented for the movies but was inspired by similar events in the books.
While Aragorn is desperately trying to lead the hobbits to Rivendell they are met by an elven lord named Glorfindel. He's described as one of the most powerful beings in Middle-earth; older and more powerful even then Elrond... He was one of the few elves the Witch-king feared, making him the perfect candidate to help Frodo escape the Ringwraith's clutches. He gives Frodo his horse and encourages him to ride on ahead, electing to hold off the Nazgûl.