Mason is a sadist who takes pleasure in acts of cruelty and sexual violence. His victims include Margot, whom he sexually assaults, and several children at a Christian summer camp founded by his father, often using the metaphor of a chocolate bar when speaking of such acts. His cruelty is so extreme that he enjoys flavoring his martinis with the tears of his victims.
Verger is introduced after Margot tries to kill him. He sends her to therapy with Hannibal Lecter, who tells her that she must allow herself to hate her brother and that it would be cathartic to kill him. Mason tells Margot that he wants a "baby Verger" to continue the family name; the implication is that he wants to father his own sister's baby. He threatens to cut her off financially if she refuses, which would leave her penniless; their father had disinherited her after she came out as a lesbian, leaving her financially dependent on Mason. In desperation, she sleeps with another of Hannibal's patients, Will Graham, in order to get pregnant. Mason retaliates by causing her to get into a car accident and having her womb surgically removed.
Mason later meets with Hannibal and arranges to go into therapy with him, mostly to find out what Margot is saying about him. Hannibal takes an immediate dislike to Mason, considering him "discourteous." Will also despises Mason, for abusing Margot, and confronts him, warning him that Hannibal is using them both.
Mason sends three of his men after Hannibal, who is hung to be eaten by Mason's pigs. However, Will releases him. Afterwards, Hannibal forces Mason to inhale a psychedelic drug, and then suggests he mutilate his own face to show him how to measure the depth of fat. Mason complies and is later found in Will's home feeding parts of his face to Will's dogs, and eating his own nose. Hannibal tries to get Will to kill Mason, but Will tells him to "do what he thinks is best." Hannibal promptly breaks Mason's neck and then readjusts it, leaving him paralyzed.
Later, Jack Crawford visits Mason in his hospital bed, where his lower face is covered by a protective mask. Claiming that his injuries were caused by him falling into the pig pen, breaking his neck and having his face eaten by the pigs, he states he is benefiting from Lecter's therapy and that he hopes to "repay him one day." When Jack leaves, Margot enters, saying she will take care of Mason - "like you took care of me."
In season 3, Mason, now severely disfigured and wheelchair bound, is aided by both Alana Bloom and his psychopathic servant Cordell. He puts out a bounty on Hannibal Lecter, who fled the country after his crimes were uncovered. He intends to have Cordell slowly torture Hannibal to death and prepare gourmet cuisine from the doctor's flesh, which Mason will eat. Meanwhile, Mason has used his sperm to create a "Verger baby" in Margot's surgically removed uterus, which he has stored inside a dead sow, but the baby is stillborn.
After Hannibal and Will are delivered to him, Mason plans on having Will's face sewn onto his own. Just before the operation is performed, Alana frees Hannibal, who proceeds to kill Cordell and help Margot and Alana - who are now lovers - milk Mason's prostate for the sperm needed to conceive an heir. Finally free of her brother, Margot drowns him in his eel tank.
Mason admired and respected his father and looked up to him. Mason's father would often stab pigs to test how fat they were; Mason found this amusing. Mason is described by Alana as being a sadist and is capable of great cruelty, going as far as to emotionally and sexually abuse children and his own sister. This is evident in the way he wants to slowly kill and consume Lecter while he is alive. He is inconsiderate of other people and their belongings, which makes Hannibal find him discourteous. He is known to drink martinis made with teardrops of children collected via tissues and carried in a small box in his jacket pocket.
- Mason's suits are made by Garrison Bespoke.
- Bryan Fuller described him as the "Joker to Hannibal Lecter's Batman".