Avus

Avus was a young Homeworlder who was known by the elder of his Great House for causing trouble. He studied many alter-time realms.

Avus once explored an alter-time realm which held a remnant of the pre-universe. Finding himself threatened by painted warriors, Avus accidentally fell into a pool of Praxis. Under the drug's influence, Avus experienced a series of lucid visions: he was Abigail's pet bird, a pilot going through a dense nebula, a human listening to Aguta's storytelling, and a guest at the unveiling of Cernunnos on Terra Primagenia. Cernunnos psychically latched onto Avus, chasing him into a vision of the Amazolian system. Cernunnos then brought Avus back to the alter-time realm, thanking him for showing the way. Avus tried to escape by shattering his mental link with Cernunnos. Finding a weakness via Cernunnos' future fate as a caged animal in George III's menagerie, Avus overcame the psychic link and returned to the Homeworld.

Only centuries afterwards would Avus fully understand his meeting with Cernunnos. Cernunnos predicted that Avus had been inspired by the experience and in the War a Homeworld would be brought down by Avus' will. (PROSE: Cobweb and Ivory)

Behind the scenes
"Avus" is latin for "Grandfather". Both Grandfather Paradox and the First Doctor are significant members of the Great Houses who were called "Grandfather".