A descendant of Dragons and the teacher of Wei Shi Lindon Arelius, Orthos is a sacred turtle of great importance to the Cradle novels. He is a sacred artist on The Path of Black Flame. Once in a duel long ago he crippled himself and was driven mad. Recently, with the help of Lindon and Little Blue he was able to regain some measure of sanity. This was further helped by his time spent in the Ghostwater (Pocket World). At the end of Ghostwater book 5, it is inferred that he has almost fully recovered from his illnesses.
In book 6, Underlord! he leaves Lindon and the others, saying that Sacred Beasts do not have to undergo a revelation to reach Underlord. Instead, they chose what they wished to become (ex: Orthos could remain a turtle, become a dragon, or even become human, as seen by Seshethkunaaz, the boy King of the Dragons). For this reason, Othos leaves and is later seen in Sacred Valley alongside Lindon's sister, Wei Shi Kelsa. It is still unknown as to what form Orthos plans on taking.
During the attack of Sacred Valley, Orthos advanced to Underlord with Lindon's help, in order to fight The Wandering Titan.