This one requires some back story. If you're familiar with The Silmarillion, this will be a very brief summary; if you're not, you should read it (though there's also a short version told by Aragorn in The Fellowship of the Ring). If you're planning to read The Silmarillion, spoiler alert. ;) This is a hard story to tell without a lot of background references, but I'll try to keep it concise. The elves were created and woke up in Arda (Middle-earth), but this was ruled by the devil Morgoth at the time (Sauron was one of Morgoth's servants). The Valar (angelic beings given governance of the world) therefore brought the elves back to Valinor, the Undying Lands and home of the Valar. Not all elves agreed to come however; these were the Avari. Some agreed to go to Valinor but turned aside along the way; these are the Sindar (Legolas was a Sindar). Three groups, however, made it Valinor: the Teleri (closest related to the Sindar), the Noldor (dark-haired, grey-eyed, lore masters and craftsmen), and the Vanyar (golden haired, poets). One of the leaders of the Teleri, Elwë Thingol, encountered on his way back to the Undying Lands (the leaders of the three groups had been taken there in advance, making him one of the Eldar, the Elves who had gone to the Undying Lands) a Maia (angelic being lesser in power than a Vala) named Melian. He fell in love with her and remained in Arda as High King of Doriath. We'll be back to him. At any rate, one of the Noldor, named Fëanor, created three jewels called silmarils, special jewels that glow and have great power. These jewels contained the light of the Two Trees of Valinor (long story). Morgoth, the devil, killed the trees and stole the jewels. Fëanor, tricked by Morgoth into blaming the Valar (sort of; again, long story) led a rebellious group of Noldor back to Middle-earth. Okay, fast forward a lot. A human man named Beren wanders into Doriath and sees Thingol's daughter Lúthien, the most beautiful person to ever live. He falls in love with her and calls her Tinúviel (nightingale). Thingol tells Beren he may marry Lúthien if he retrieves one of the silmarils from Morgoth's crown. With Lúthien's help, Beren does but loses one of his hands (hence his name Erchamion, One-Hand). Beren dies and Lúthien dies of grief. However, they are given permission to return to the world, but Lúthien is now mortal. They retire to Tol Galen (the Green Isle) and have a son named Dior. Dior is the grandfather of Elrond and Elros (Elros is the ancestor of the kings of Númenor and hence an ancestor of Aragorn). Lúthien wears the silmaril around her neck. This summary does not do justice to Tolkien's version, so seriously go read it. ;)