Arien was originally a Maia in service of the Valië Vána the Ever-young, though in some writings she served Varda the Queen of the Valar. Arien from the beginning was originally a spirit of fire whom Melkor was unable to deceive nor draw her to his service. The eyes of Arien were said to be too bright for even the Eldar to look upon. In the Days of the Trees, she tended to the golden flower gardens of Vána. Arien would water the flowers with great bright dews collected from the great golden Tree Laurelin of Valinor. Arien later was chosen by the Valar to carry the vessel of the Sun because she was the only one who was not afraid and could bear the heat of the great Tree Laurelin, and so was unhurt by it. While in Valinor, Arien took a form similar to that of the Valar, but when Arien left Valinor, she forsook the raiment like the Valar and became a "naked flame of fire, terrible in the fullness of her splendour".
Later on, when the great Two Trees of Valinor were destroyed by Morgoth and Ungoliant, the great golden Tree Laurelin managed to produce one last golden fruit before it died away. Subsequently, Aulë the Great Smith of the Valar, then crafted a vessel to hold the precious golden fruit and that is how the fashioning of the Sun came about. So after the vessel for the Sun, also named Anar, was made ready, Arien carried the vessel of the Sun away up into the Heavens giving light to the World. However, it took Tilion (a Maia who was one of the Vala Oromë's hunters) who was chosen to steer the Moon, to traverse seven times before the vessel of the Sun was ready. Then Anar rose in glory, and the first dawn of the Sun was like a great fire glowing upon the towers of the great mountains of the Pelóri of Aman . And the clouds of Middle-earth was kindled and there was heard the sound of many waterfalls. Then indeed Morgoth was dismayed and he descended to the lowest pit of Angband his stronghold and also withdrew all his servants as well. Then Morgoth sent forth great reeks and darkness of clouds to hide his land from the the light of the Daystar. Consequently, by the coming and going of the Sun, the Valar reckoned the days thereafter until the Change of the World. Of Arien, Morgoth feared with a great fear but dared not come close to her, having indeed no power to do so now. Also, Morgoth hid himself as well as his servants with shadows from the glance of Arien whose eyes could not be endured for long.
The Maia Arien was more powerful than the Maia Tilion the Guardian of the Moon, who occasionally followed Arien through the night sky but when catching up to her, Tilion became burned and blackened by Arien's heat when in close proximity to her. The light in Valinor was fairer than in Middle-earth because the Sun rested there. Therefore, the lights of heaven drew nearer to that land in that region. Moreover, the Valar stored the great radiance of the Sun in many vessels, vats, and pools to use for their comfort in times of darkness. As Arien was the "Guardian of the Sun", she was one of the most loved of the Maiar by mortal Men, for her first journey across the sky was the signal of theAwakening of Men.
Urien and Urwendi are the earlier names for Arien, which both meant "Maiden of Fire".
Other versions of the legendarium
In other writings, Morgoth wanted to claim Arien as a wife, and ravished her, upon which she abandoned her body and "died", leaving the Sun to travel through the skies uncontrollably and burning parts of Arda.
It was told that Arien and her maidens, before the rising of the Sun, entered into Fôs Almir which was a bath of flame that would make one pure.
- The History of Middle-earth, Vol.5: The Lost Road and Other Writings, VI."Quenta Silmarillion"
- The Silmarillion, Quenta Silmarillion, Chapter Eleven."Of the Sun and Moon"
- The Lost Road and Other Writings, Part Two: Quenta Silmarillion, "Of the Sun and Moon and the Hiding of Valinor"
- The Silmarillion, Quenta Silmarillion, Chapter XI: "Of the Sun and Moon and the Hiding of Valinor"
- The Silmarillion, Appendix: Elements in Quenya and Sindarin names
- The History of Middle-earth, Vol. 1: The Book of Lost Tales Part One, Appendix: Names in the Lost Tales – Part I
- The History of Middle-earth, Vol. 1: The Book of Lost Tales Part One, IX: "The Hiding of Valinor"
- The Book of Lost Tales Part One, Chapter 8: "Of the Sun and Moon"