Complex sentence: Elladan and Elrohir are fictional characters in J. R. R. Tolkien's Middle-earth, the twin sons of Elrond Half-elven and Celebrían.
Split into simpler sentences: Elladan and Elrohir are fictional characters in J. R. R. Tolkien's Middle-earth. They are the twin sons of Elrond Half-elven and Celebrían.