Vulcan is the current parent star of ArcNyx. Before becoming a star 2 billion years ago, he was a lost Transcendent of a distant universe. It is not uncommon for individuals to remain existing after the collapse of a universe, they roam about The Multiverse, either living the rest of their life as a “lostkind” or enter another universe as a refugee.
In Vulcan’s case, he approached Cassandra Fusallo in the early stages of her universe creation, requesting to help in any kind of way. Missing a parent star as a host, Cassandra let him in, on the condition that he would become the star in Arc and Nyx, supporting life after he helped created the planets.
He and Cassandra then created 17 demigod children, to assist in the development of Arc and Nyx, as well as to create a genetic mark on the universes.
Throughout human history, Vulcan has never made a physical appearance on either Arc and Nyx. However, in both Arc and Nyx, it is known that he supports humanity during their battles with Cassandra-created divinities, blessing them with swathes of firepower.
It is believed that prior to his solar form, Vulcan was an anthropomorphic Greek Eagle, with flaming wings.