The elves of Mirkwood had a secret, a rather big secret it was too. The elves in the other kingdoms – Rivendell and Lothlorien- knew that the King and Queen of Mirkwood had a son, but what they did not know was that Legolas was not an only child, he was a twin. His twin's name is Mardion.
The only elves outside Mirkwood that knew he Legolas is a twin are, Lord Elrond of Rivendell and Lady Galadriel and Lord Celeborn. They are the only ones who know because Lord Elrond and Lady Galadriel can see into the future. Lady Galadriel could not, not tell her husband about what she saw when she saw that twins would be born in Mirkwood.
Unfortunately Lady Galadriel also saw that the youngest of the twins (Mardion (By one minuet)) would be in major trouble if he stayed in Middle Earth.
The Valar, though they do not usually intervene in things that go on in Middle Earth, felt that they had to do something to help the elves. They knew how valued an elfling was to the elfish race, so they gave the young child magic and transported him to a different dimension called Earth. Also, so not to confuse the child when he got back home they decided to go into his dreams each night, telling him that everything would be okay and he would be able to get back home to Middle Earth when he was seventeen. They would tell him that he would be mortal while living on Earth so he would age normally and his ears would be hidden until he was of age in the wizarding world (Seventeen). They would also remind him that when he got beck home that he would become an elf once again and he would look like an elfling would at the age of seventeen, (About the age of 5)
However, when the Valar transported him there they did not know where he would end up. Luckily for them he was put on the doorstep of a young couple who had just graduated from their school, Hogwarts School of Witchcraft and Wizardry, the young couple just married took him in. They did not know his name, so they gave him one, on Earth he was now known as Harry James Potter, son of Lily and James Potter.
Or maybe it was unlucky that the child was transported to the young couples doorstep as 15 months later, on the 31st October, they were killed by Voldemort, the Dark Lord of the Wizarding World. Harry survived and was sent to live with Lily's older sister and her family. He was not treated very well while he was there, he was locked in the cupboard under the stairs for ten years of his life, he was beaten, even more so when he got his Hogwarts letter, but none of this matted to him, as he knew when he was seventeen he would be able to leave all that behind and live with his real family, his father, the King of Mirkwood and his brother Legolas.
So with all this in mind Harry pushed on and he became 'The Saviour of the Wizarding World' when he defeated Voldemort in the 'Final Battle' as it was named.
The Wizarding World was shocked to hear that only a few days after the battle their saviour had gone missing, it was like he vanished in to thin air, which he did but the people did not know that, nor did they need to know that.