Dúathiel has a complex hhistory, which spans much of Middle-Earth as we know it. Her beginnings are unclear, her race is unknown and her creator(s) are lost to the index of Middle-Earth. She was present in the realm of Mordor long before Sauron was. She was an immmediate friend, supporter, companion and ally of Morgoth (Melkor) upon his arrival in Middle-Earth. She learned much from Morgoth which improved her already great powers to that as which she was the 3rd most powerful being in Middle-Earth. (That after Sauron and Morgoth). She was dismissed as a powerful being in the eyes of Sauron, and from that moment on she had a bitter rivalry with him for a place at Morgoth’s side. Sauron came out the more powerful of the two, and she was forced to resign to his command – an act which has bothered her ever since. After the banishment of Morgoth, Dúrathiel retreated to her land where she rested and regained her forces, waiting for her chance to take her rightful place as overlord of Middle-Earth. After many great battles, deaths and events had passed, Sauron came to her land, looking to claim it for his own. He was unaware that this desolate land was Dúathiel’s, and he began to build Barad-Dur for his own purposes. She was scared of Sauron, for he had greater power than she did, but seeing that her land was being overtaken, she flew to Barad-Dur upon the back of Rhach to demand that he leave her domain. Sauron then mutated into his greatest form, and seeing that she could do nothing to stop this invasion, she welcomed it. Mordor was now in the hands of Sauron – and his servants. Dúathiel know saw that she could still become overlord even though Sauron was in her territory. She relented to take a place at Sauron’s side, and she is now his most powerful minion. In respect of her co-operation, Sauron gave to Dúathiel a pendant, which now gave her much more power, but still it could not rival that of her master. He also gave to her the title of Queen of Darkness and Despair, for even he could see that she was indeed the most corrupted creature ever.
Now she roams Middle-Earth, seeking those who wish to be one with the Dark Lord’s ways. She answers solely to Sauron (which she still despises to do, but she will do anything and everything that the Dark Lord asks of her.) It is only a matter of time before her chance will come.