Aluin, called The Eldest and The Ainu of Time is revered as the First of the Ainur, the first of Eru’s thoughts to be given shape and voice and the mightiest among the Alahíri, those spirits who remained in the Timeless Halls with Eru Ilúvatar. He had sent his three sons – Danuin, Ranuin, and Fanuin – to aid the Valar in creating the physical time within Arda.
Tolkien's Work[]
Initially Aluin was to be a great Ainu of Time and the eldest Ainu of all. He had his three sons make cords and devices for Manwë to help control the Sun and the Moon. Given that they played no part in the Silmarillion, a GameMaster could use their names to fill in critical spots of Middle-earth and beyond. The Three Ainur of Time could be reinterpreted as servants of Vaire the Weaver of Time or they could be the three direct servants to Aluin who stayed inside the Timeless Halls. Given that the Ainur were all created at the same time from Eru's thought, Aluin may instead be considered something else instead of the eldest Ainu of all, or he may have been the first Aniu to spring from Eru's thoughts/creation.