Complex sentence: Arwen first appears in the text of "The Lord of the Rings" in Rivendell, shortly after Frodo Baggins awoke in the House of Elrond: she sat beside her father at the celebratory feast.
Split into simpler sentences: Arwen first appears in the text of "The Lord of the Rings" in Rivendell shortly after Frodo Baggins awoke in the House of Elrond. She sat beside her father at the celebratory feast.