|Cassie and John|
Her mother Amelia was dating John and their love resulted in the birth of Cassie. Amelia moved out of Chance Harbor after the boatyard fire. Cassie grew up without a father and knew nothing about him. After the death of Amelia cassie moved to Chance Harbor and started to hear and learn about her father.
Cassie began to learn about her father when she moved to Chance Harbor from the people who knew him. She learned about her father while learning about her dark magic and the other family she came from. She found out that her father survived the boatyard fire from Jake's memories. She found her father's medallion and digged up his grave with Jake's help to find it with a skeleton of an animal inside. She began to learn about the terrible deeds he has done while learning about him.
In Return, Cassie finally met her father though she wasn't too happy to see him. She came to see him again for answers. She was later kidnapped by Eben and John came with Jake to free her. He was attacked by Cassie who was spelled by Eben to kill John. Cassie and the circle were able to stop the spell and saved John. John began to stay at Chance Harbor to protect Cassie.
In Lucky, Cassie began question John about his relationship with her mother. She demonstrate her dark magic to him and he told her about the dangers of dark magic. She began to be suspicious about her father when he was looking for a sway. John told her that the sway was used to give the witch hunters power from a member of the circle. John was stabbed by Ethan and she stopped him. She was under the influence of dark magic to kill him until John stopped her. At the house, John was patching up the wound and told Cassie to avoid Ethan. He told her to stop using magic due to the dangers from it.
In Curse, John fake the curse by killing birds while Cassie and Adam were sleeping together. They saw the dead birds and John told them that they are responsible for it because of the curse. She and John went to see Jane about the curse and learned that a person from the circle will die. John and the circle were prepared to make an elixir to erase the feelings for Adam and Cassie. Adam and Cassie drank the elixir though she reveal to her father that she still has feelings for Adam and was crying due to Adam not loving her.
In Sacrifice , John came by to check on Cassie with her struggle with her feeling for Adam that she hasn't told the circle. John was able to meet Samuel after he went to see Jake and Cassie. They learned about Eben's plan to summon demons. Cassie learned that her father has summoned demons including the one that killed Nick. They tried to stop Eben from getting powers from the demons. John used his dark magic to kill Samuel and everyone else saw that John still has his magic. John revealed his plan to stop Eben by using crystals where Cassie has one already.
In Crystal, John told the others to find their own crystals from their own families and Cassie told him to visit Jane at her house. Cassie learned about her father's plan to have children from the circle and that she isn't the only Blackwell in the circle.
In Traitor, She talked to John about how he was in a relationship with Diana's mother Elizabeth when his relationship with Amelia was rough. Cassie told him that she wanted to be rid of the witch hunters by finding the crystal. Faye was able to find a crystal that is out of power and John was going to help recharge it by asking Cassie to bring Diana.