Before speculating on Celeborn's future role on "The Rings of Power," let's take a look at what J. R. R. Tolkien himself says about the Elven lord. When you dig into Celeborn's backstory, one thing becomes clear right away: there isn't much there.
That's not to say that Celeborn doesn't come up much. He does. He's right there with Galadriel throughout the First, Second, and Third ages of Middle-earth history. Celeborn is even one of the last Elves we hear about in the Fourth Age that follows "The Lord of the Rings." The Prologue to "The Fellowship of the Ring" even ends with the line, "It is said that Celeborn went to dwell [in Rivendell] after the departure of Galadriel; but there is no record of the day when at last he sought the Grey Havens, and with him went the last living memory of the Elder Days in Middle-earth."
Despite the frequency of mentions, Celeborn remains hazy for two reasons. First, there isn't much detail about him or what he does. Second, when there is detail, it tends to be inconsistent over the course of Tolkien's endless drafts and rewrites. Even so, there's enough there to paint a basic picture.
Celeborn and Galadriel meet in the First Age, fall in love, and eventually head east, looking for greener pastures. Early in the Second Age, they have a daughter named Celebrían. The major difference from the show here is that Celeborn doesn't get lost in a war. He's with Galadriel the whole time, and the two quickly become one of the premier power couples in Middle-earth. They live in Gil-galad's kingdom for a while at the beginning of the Second Age and then relocate further east again, eventually ending up in Eregion with future ring-maker Celebrimbor.
