J.R.R. Tolkien's The Lord of the Rings is one of those works that never goes out of style, brimming with such rich characters and extensive lore. It's why new fan theories are continually being formed, such as the Reddit theory that Frodo doesn't even know Legolas' name, despite them meeting in The Fellowship of the Ring.
Posted on Reddit by user applecub, the theory posits that Legolas' name slipped Frodo's mind since their introduction was brief and overshadowed by the daunting task of destroying the One Ring. By the time they reunited in Rivendell, Frodo didn't ask Legolas for his name to avoid offending him. After months of being separated from the Fellowship and the trauma he experienced on the journey to Mordor, it would make sense that Frodo might forget Legolas' name.
Frodo and Legolas Did Not Have Many Interactions
When the Fellowship was formed in Rivendell, Legolas was fairly quiet, which is normal for his introverted character. Although Frodo may have been introduced to Legolas, the content of that fateful meeting would understandably override any other information. The most important member of the Fellowship, besides Frodo, would have been Aragorn, or, as the Hobbit knew him at the time, Strider. Aragorn had helped Frodo to survive the Ringwraith's attack and led his companions most of the way to Rivendell. However, Legolas was a new figure in Frodo's life.
It also doesn't help that, after the skirmish at Amon Hen, where Boromir died, Frodo and Sam separated from the rest of the Fellowship so that they could make their way to Mordor. This means that Frodo really didn't spend all that much time with Legolas in the first place.
How Return of the King Suggests Frodo Forgot Legolas' Name
The Reddit theory notably brings up the Fellowship's reunion in The Return of the King, where it's clear Frodo doesn't say Legolas' name. When Gimli walks through the door, Frodo says his name with glee. Frodo smiles when Legolas follows, but his mouth hangs open slightly -- almost as if he has forgotten the Elf's name.
Whether Frodo actually knows Legolas' name is up for debate, as fans don't actually hear Frodo say his name many times in the film trilogy. But this fan theory clearly holds some water, with it being entirely possible that, even if Frodo did know his name, he absolutely forgot it through no fault of his own. Frodo was burdened with an important purpose, so trivial information like an Elf's name could've easily slipped his mind.