Lord Cassius is described to possess many of Keefe's characteristics, with more slicked-back blond hair, and maintains a neater attire. He is also tall and lean.
His smile is said to be "oily, dripping with insincerity."
Sophie meets Keefe and Lord Cassius in the Level 4 wing at Foxfire. Sophie notices that Keefe is always dejected whenever his father is near. Lord Cassius describes Tiergan as an "infamous mentor" after Tiergan saves Sophie from sharing her ability as a Telepath.
After Sophie's telepathy is revealed to the public, Keefe describes his father as very smug. Apparently, Cassius had guessed that Sophie was Tiergan's prodigy. Keefe says that his father must always be right, and that he always is.
Sophie, the bodyguards, Mr. Forkle, and her friends went to Candleshade, to see if they could find anything that Keefe left behind for them. They met Lord Cassius there, and he had a conversation with them.
In Nightfall, Lord Cassius informs Keefe and Sophie of where Vespera hid her signature in Atlantis, proving his worth to the Black Swan, later joining the organization. It was said earlier that Fitz had suspected Lord Cassius to have been the one to break Lady Gisela out of jail, something Keefe severely doubts, stating that his father cares too much about his reputation to rescue her.
Lady Gisela was Lord Cassius's wife. He confesses that he did feel love for her, though he lost it when Keefe, Sophie, Fitz, and Biana found her on Mount Everest with the Neverseen. He regards her as an enemy after her betrayal, and works with Sophie and Fitz in order to uncover his shattered memories in Book 8: Legacy.
- Keefe (son)
Lord Cassius has a poor relationship with Keefe. From a young age, Lord Cassius verbally abused and targeted Keefe, and constantly thrusted unrealistic expectations on his shoulders. He often insults or scoffs at Keefe. This repeated abuse affected Keefe and his view on himself and others, something Lord Cassius seems oblivious to. From a young age, Keefe thought of Alden as a father figure rather than his father, and began wishing that he was a Vacker. In Nightfall, Lord Cassius forced his son to live with him by threatening to withhold vital information that the Black Swan desperately needed. In recent books, he seems to care about Keefe more, though Keefe remains annoyed with him, often disregarding Lord Cassius altogether. In Legacy, it is revealed that Lord Cassius does care for Keefe, but is incredibly reluctant to show any kind of affection due to his convoluted views on love.
- Ro (son's bodyguard/nuisance)
Ro dislikes Lord Cassius immensely, and goes out of her way to make his life miserable, feeding him harmful amoebas and insulting him every chance that she gets. Lord Cassius generally regards her as a nuisance, though he tolerates her as Keefe's bodyguard.
- Sophie Foster (son's friend/forced acquaintance)
Sophie is generally hostile towards Lord Cassius, hating him for his treatment of Keefe. She hates that he is a member of The Black Swan, and originally believed that he was a member of the Neverseen. Lord Cassius has begrudging respect towards Sophie, though he is very cold towards her. He has faith in her abilities, allowing her to search his memories in Legacy.
- Dad of the Year
- Lord Snootypants
- Daddy Dearest
- Lord Annoyingpants
- Lord Jerkypants
- Lord Cassius is an author, having written a book about Empathy: The Heart of the Matter. Keefe finds this book boring and dull, describing his father as a "torturer of innocent readers." However, in later books, Keefe admits that he had learned about the head and heart emotions from the book.
- He is a powerful and talented Empath, working for the Council as a member of the nobility.
- Lord Cassius is extremely snobbish and vain, having an entire room dedicated to his accomplishments.
- His name, Cassius means "empty" or "vain."
- Cassius also means "hollow" in Latin
- It takes Lord Cassius exactly 31 minutes to comb his hair.
“Do you know we have an entire room at our house dedicated to the Wonder That Is Him?”
“Where there is a will, there is a way.”
“Back to nag me already? You seriously need to get yourself a hobby. I hear spelunking's fun. Oooh, or you could try swimming with the krakens! I doubt they'd eat you—but maybe we'll get lucky!”
“Everything I withhold is for his own good. Love... convolutes things”
“I fear the reality is simply that while it may impossible to lie to an Empath, it's far, far too easy for us to lie to ourselves.”
"And Lord Cassius, for all of his bravado, was very, very weak."
- Sophie in Legacy