Sirenians are aquatic, herbivorous mammalian beings with elongated necks, two large eyes on each side of their slender heads, and prehensile feelers on the front of their face, which provides enhanced sensory perception. Sirenians vary in length from 1 to 3 meters, from tail to head, and generally stand upright about half their total body length. They have large fins used for underwater movement and a large tail they can move and balance upright on. When they want to move more quickly on land and/or swim they use their fins.

The Sirenians are native to Olleanus, a massive planet whose surface is almost entirely covered in water. They constructed massive underwater cities and established a neutral zone for trade, inviting other factions to participate. The Sirenians quickly became known as facilitators of peaceful commerce and mediators of conflicts that arose between factions. Everything from trade route disputes, technology bans and even inter-faction wars. With conflict and unrest around the fading light of the universe, the Sirenians were stretched too thin and were unable to help as many factions as they would have liked. As they learned of so many other factions setting out to locate the Last Light, they set out with the goal to help as many as they can along the way. Their ultimate goal is to establish a new center of peace for all factions, but to do this, they must make it to the last light.