The Lord of the Rings: The Rings of Power will introduce Elros, the twin brother of Elrond, in its upcoming third season, giving fuller shape to a key strand of Tolkien lore the series has so far only hinted at. Elros founded the island kingdom of Númenor and began the royal bloodline of men that eventually led to Aragorn, while Elrond chose immortality as an elf; the season 3 flashback depicts the pivotal moment Elros tells his brother he has chosen mortality, ahead of Elrond's present-day journey to Númenor to seek help against Sauron.

Robert Aramayo, who already plays Elrond, takes on the dual role of Elros as well, with the brothers written as identical twins despite their diverging fates. Showrunners J.D. Payne and Patrick McKay say the flashback lets Elrond confront grief over losing "the person who was closest to him," while Aramayo describes approaching Elros through "earth" and "humanness" versus Elrond's "wings and air", drawing on their mother Elwing's transformation into a bird. The scene, occurring after the deaths of their parents Eärendil and Elwing, underscores loss as a defining theme of Elrond's arc as the series heads toward its Sauron-focused conflict.