Elladan (Sindarin for Elf-Man) is the oldest of the twins who Celebrían, the wife of Elrond, gave birth to in Third Age 130 (making him about 2,888 years old). His twin brother is Elrohir and his little sister is the wondrous Arwen Evenstar, born 111 years later. Elladan was so named, 'Elf-Man', as a token of his ancestry; he was descended not only from the royal houses of the Eldar, but also from the Three Houses of the Edain. Elladan and Elrohir look so much alike that it is hard to tell them apart, both dark-haired and grey-eyed. He can be distinguished from his brother by the colours of his clothing: his cloak is orange with teal trim.
Many centuries later, Celebrían went on a journey into the south to visit her own mother, Galadriel, in the land of Lothlórien. In the Redhorn Pass, she was captured by Orcs, and she was tortured in their dens. Elladan rode with his brother to rescue her, but by the time they reached her she had received a poisonous wound. Though their father healed her, she would not remain in Middle-earth, and sailed into the West the following year. After this loss, Elladan and Elrohir were filled with hatred of the Orcs, often riding against them with the Northern Dúnedain.
In the year T.A. 2,933, they rode against Orcs with Arathorn II, Chieftain of the Dúnedain. Arathorn was slain in that encounter when an Orc-arrow pierced his eye, so Elladan and Elrohir took his young son, Aragorn, to be fostered by their father. Aragorn became good friends with the brothers and often adventured alongside them. They remained in contact with Aragorn in his guise as "Strider" and continued to support him. As the War of the Ring begins, the brothers' main role is to scout the land and prepare the way for the Fellowship, but later they will take a more active part.
After the War of the Ring, the brothers return to their father's house at Rivendell, and will remain there even after he passes across the Sea. Like their sister Arwen, the sons of Elrond Half-elven are granted the choice of whether to leave Middle-earth for the Undying Lands, or remain there and become Mortal as Men. Elladan had such a bond with his brother that they must surely choose alike, but what choice they will make in the end remains to be seen.
Elladan (The Trollshaws)
Later, Elladan and Elrohir can be found at Thorenhad, the camp they established in the Bruinen Gorges in the midst of the Trollshaws. This is the base for the scouts who patrol the region, for Rangers and friendly visitors, and for many other purposes. Here Elladan helps locate the lone Nazgûl who escaped the wrath of the Bruinen.
Later, they briefly return to the Last Homely House to receive a mission from their father: the gathering of the Grey Company. They afterwards return to Thorenhad to begin this mission. Once the Grey Company has assembled in Rivendell, the Sons of Elrond can temporarily be found at Elrond's Stables.
- "The Nazgûl has fled once again, but he will be found."
- "You have been a great service to us <name>."
-  Intro (High Elf): Into Darkness Falls a Star
-  The Sons of Elrond
-  Wolves at Their Backs
-  Ost Thondol
-  The Ford of Bruinen - Skirmish
- [...] Mission: The Further Adventures of Bilbo Baggins, Chapter 1
-  The Corcur Arise
-  Raid: The Corcur of Helegrod - Raid
-  Volume I, Book 4, Chapter 1: Where is the Horse and the Rider?
-  Volume I, Book 4, Chapter 2: The Missing Rider
-  Volume I, Book 4, Chapter 3: The Wisdom of Lord Glorfindel
-  Volume I, Book 4, Chapter 4: Regaining the Trail
-  Volume I, Book 4, Chapter 5: Hiding in the Dark
-  Volume I, Book 4, Chapter 6: The Knowledge of the Onodrim
-  Volume I, Book 4, Chapter 7: The Aid of Mirkwood
-  Volume III, Book 1, Prologue, Instance: Messages from Lórien - Solo only
-  Volume III, Book 2, Instance: An Echo of Days Past
Elladan (Ered Luin)
Together with Elrohir he has arrived to the area because of a curious dream their father had. He has organized a temporary Elven camp just outside the ruined Refuge of Edhelion and there he organizes the research and those who have journeyed to the Blue Mountains to quell the evil timings that have begun to spread throughout the Middle-earth.
-  Intro (Dwarf/Elf): Elrond's Errand
-  Intro (Dwarf/Elf): Elrond's Dream
-  Intro (Dwarf/Elf): Honing Your Skills
-  Intro (Dwarf/Elf): Where Skorgrím Fell
-  Intro (Dwarf/Elf): Where Skorgrím Sleeps
-  Intro (Dwarf/Elf): The Footprints of Blood
-  Intro (Dwarf/Elf), Instance: Skorgrím's Tomb
-  Prologue (High Elf): Reflections of the Past
-  Volume III, Book 4, A Full History - Elf
-  Volume III, Book 4, Instance: The Rescue
-  Interlude: Many Worries
Elladan (Central Gondor)
-  Retaking Pelargir
Elladan (March of the King)
-  Friend or Foe
Elladan (The Wastes)