From the moment Caius was turned, Lucian knew there was something about his transformation that was incomplete. It was he who first said Caius was a Vampire Spawn and not a True Vampire, but there was very little he knew about Vampire Spawns. Actually, there was very little that anyone anywhere knew about Vampire Spawns.
Whenever a Vampire turns a person, it's for a purpose and that purpose can never really be served if the turned can't even access the true 'worth' of being a Vampire.
It took a different kind of vendetta for Anthenodora to do what she did to Caius; She didn't want him strong and didn't need him to serve her. She just needed him to change enough to make Lucian be forced to make the tough decision to end his own son.
Anyway, it was because of the lack of any real knowledge on Vampire Spawns that Caius felt he could get away with embracing his Vampirism without divulging the truth to his father for fear of how he would take it.
