"Do you really wish to know?"
Spoilers from the books and/or adaptations to follow!
Anton de Creigiau the Younger was the son of Anton the Elder, half-brother to Bryton, and the biological father to Delwyn. He also had heterochromia: one eye is brown and the other is green.
Anton was banished from the castle after an affair with his brother's wife, Lady Sérlait de Creigiau. Like his father before him, he was also a werecat.