Interesting Facts: Where The Kingdom of the Woodland Realm Began and Where it is Going
Thranduil is a character that first appeared by name in "The Lord of the Rings on July 29, 1954--not “The Silmarillion” as that book was published on September 15, 1977 after Tolkien died. Now, his first original appearance was September 21, 1937 (80 years from 2017) in “The Hobbit”. He had no name. His son was never mentioned.
The was film invention and felt it would follow that if LOTR was the sequel to The Hobbit, then Thranduil would be named and his son Legolas would be there (though in the book, neither have names and Legolas was never there). His father Oropher is not mentioned in “The Silmarillion”, but in the “Unfinished Tales” where it stated that “Oropher had the wisdom to foresee that peace would not return unless Sauron was overcome.” This was in reference to the War of the Last Alliance (p. 258).
On page 280, Oropher is described as “King of the Silvan Elves east of Anduin, being disturbed by rumors of the rising power of Sauron, had left their ancient dwelling about Amon Lanc, across the river from their kin in Lórien.” This occurred long before the War of the Last Alliance (mentioned in the UT). He moved three times before he ended up in what we know as Eryn Galen (aka Mirkwood).
That is how I know what I know to write what I write about Thranduil and the Kingdom of the Woodland Realm. It is original POV, but there is not one thing written that goes outside the historical events. I wouldn’t do that. I want it be plausible and worthy of true fan fiction. And if Tolkien were here, I would want him to say ‘well done, I could see that’.