Corvus was originally the Celestrian guardian of Wormwood Creek. While protecting it, he is injured by the Gittish Empire and able to be visibly seen by the humans living there. He develops a relationship with Serena while he is healing.
When the Gittish Empire returns to attack the town, Corvus attempts to go and meet them in battle. However, Serena, fearing for Corvus' health, convinces him to go and hide in a cave while her father attempts to thwart the empire. Once in the cave, Corvus decides that he must go and attempt to protect the village, even if it kills him. Serena offers him a potion which she claims will help heal him, but is instead of a sleeping potion. Corvus drinks it only to become incapacitated as the imperial troops enter the cave. Her father betrays him and Serena by allowing the Gittish Empire to take Corvus to maintain Wormwood's safety. When Corvus wakes up for a little bit he hears Gittish soldiers thanking the old man for complying and believes Serena gave him the sleeping drought to capture him. Serena and her father are murdered with Corvus powerless to stop the empire's men. He is then taken captive by the empire.
Corvus is taken to Oubliette which is the prison deep beneath Gittingham Palace. There, he is completely forgotten by his peers. He develops a deep resentment against humans, including Serena whom he believes betrayed him. While being imprisoned, Corvus' evil power grows until he becomes powerful enough to strike the Realm of the Almighty and greatly injuring its king, Zenus, and forcing him into seclusion. He also revives Barbarus, the evil dragon killed by Greygnarl some 300 years earlier. Although he has become ultra-powerful, he remains in prison in the Gittish Empire. Allowing the empire to pursue his goal of destroying humans and Celestrians alike.
When finally confronted by the hero. Corvus attacks the hero's party realizing that the hero is unable to attack him due to his superior rank as a Celestrian. He then ascends with Barbarus to the Realm of the Almighty, corrupting it into the Realm of the Mighty.
Aided by the ghost of Serena, the hero ascends to the Realm of the Mighty, defeating Corvus by becoming mortal and battling him. Corvus is surprised by the hero's newly found mortality, and seals himself in a chrysalis of dark energy. The Hero confronts Corvus, but Corvus sends Barbarus to attack the hero in his stead. After Barbarus' defeat, Corvus, having reached a fully demonic form (similar to Psaro's Secret of Evolution transformation) again battles the hero and loses. After being defeated, he prepares an attack powerful enough to destroy everything. However, he is stopped at the last moment by Serena, who appears in front of him and explains to him what really happened, including how she had always been searching for him, even after her death. Moved by Serena's words, Corvus realizes that he has been wrong the entire time and reverts to his Celestrian form. He then apologizes to Serena for thinking that she had betrayed him and thanks the Hero/Heroine for stopping him, acknowledging the hero as Aquila's student. Afterwards, he and Serena ascend into the sky and turn into stars along with the other Celestrians.