Zachary Cain is killed in Bitten by the Pack because he was part of the uprising against the Pack. He was tortured then murdered by full genital castration with a cattle bander by Clayton Danvers. He was very strong, but also very stupid. He is mentioned in The Awakening by Liam and Ramon Santos, who think Derek Souza is his son by his looks. This is true, as it is acknowledged by Zachary's father, Theo Cain. Ramon describes Cains as: "Big as a house. Ugly as a mud fence. Dumb as a brick." He was also known to have another son, but only one who died in a fight with another werewolf.
Very tall, and blond hair. Zachary is very strong. Elena estimates he is 7 feet tall.
"His shoulders spanned half the [alley]. Dark blond hair topped a face with bulldog features." ~ Description made by Elena Michaels.
In Bitten TV Show, however, he had brown hair not blond.
Bitten TV Show
He had a girlfriend named Amber and he told her about being a wolf. She wanted to be like Elena Michaels by being turned, something that he refused to do. Due to Elena telling Clayton about her, Clay seemingly killed him.
However, it is revealed in season two, episode nine "Scavenger's Daughter" that he survived as he reveals that clay did not kill him but removed his genitalia by cutting it off. He then fights Logan Jonsen to get his revenge on the pack for doing what they did to him. luckily Logan manages to choke him out before he transforms in front of a crowd in the process. Logan then informs him about the undoing and the effects it's having on the witches and werewolves. He also informed him about the witches dying and the curse on the werewolves lifting which means come the next day, they"ll either be human or wolf for the rest of their lives.
Cain then reveals to Logan that he's been keeping his girlfriend Amber on life support since she made it halfway through the change which resulted in it locking her body into a twisted disaster of a body and made her become brain dead. unfortunately He then takes her off of it and says goodbye. He then begins to cry as he grieves. He then decides to join the pack in order to stop Alister and Clara's sinister plan to kill all of the witches and take possession of Savannah's body.
Having nothing to live for, Cain sacrificed himself to help Clay and welcomed death to be reunited with his Amber. It is later revealed that Cain survived his wounds, when he appears in Season 3.