Elrond (Hugo Weaving)
Rivendell's master elf doesn't make much of an appearance in The Two Towers, but that doesn't stop him from trying to do the job of all fathers: protecting his little girl from boys. Well, maybe being a few thousand years old means Arwen isn't exactly a "little girl," but Elrond still warns her against giving her heart to Aragorn, a mortal man.
Elrond desires her to follow the rest of her people over the sea, back to Valinor. He knows that the time of the elves has come to an end in Middle-earth, it is time for them to leave. But Arwen's stubborn and wishes to stay with the boy—or eight-seven-year-old man—she loves, so Elrond has to get all dark and describe to her the pain of even the best possible scenario:
ELROND: Aragorn will die, and there will be no comfort for you; no comfort to ease the pain of his passing. He will come to death: an image of the splendor of the kings of Men, in glory undimmed before the breaking of the world.
Well okay, that doesn't sound like a bad way to go. Elrond seems to have a lot of faith in Aragorn… so why try to dissuade Arwen from staying with him. Well…
ELROND: But you, my daughter, you will linger on in darkness and in doubt, as nightfall in winter that comes without a star. Here you will dwell, bound to your grief under the fading trees, until all the world is changed, and the long years of your life are utterly spent.
Wow, Elrond isn't pulling any punches with his description of her fate. He even pulls out the old "A im, ú-'erin veleth lîn?" Translation: "Do I not also have your love?" Not wanting your daughter to deal with an eternity of pain and loss and loneliness actually makes a lot of sense—but then why can we not help but hope she decides to stay?