
Disclaimer: I do not own any of the characters that were created by J.R.R. Tolkien or C.S. Lewis. I'm not making any profit by this writing, it is done purely for my own pleasure (and hopefully for others' entertainment).
I created an original character as my user identity at a Tolkien discussion board. She's an Elf, and her name is Barufiniel (in Sindarin, and Varnafindë in Quenya). I've since developed her family into a small tree of ancestors, who may or may not appear in stories at this site. Rameldir - who has appeared - is her father. Calimon is Rameldir's friend, and Rameldir later marries the sister of Calimon's son-in-law.
Some generations back I've invented fictitious siblings and children of Tolkien's existing characters, in such cases where the total number of children was not specified, and it was not otherwise obvious that there would be no more siblings. Thus, my original characters are descended from some of the known characters from The Silmarillion.
Why then am I mentioning C.S. Lewis at all? He wrote about Narnia, didn't he, not about Elves and Silmarils?
Well, there is also cross-over ...
P.S.
When I state that one of my favorite authors is "Celegorm and Curufin" (at http://www.fanfiction.net/u/1539421/Celegorm_and_Curufin ), I should also add that on that account I am Celegorm, writing with a friend.