Alma Jensson (née Cardinale) is Alistair's mother, and a decendent from the North American branch of the famous Cardinale line of witches. She's the middle child of Anthony and Angela Cardinale. She was born to Anthony and Angela Cardinale on the 4th March 1955 in Verona, Italy and raised in Sunrise, Louisiana from the age of 6. She's the wife of Mark Jensson, and also the mother of Harriet, Richard and Claudia Jensson, as well as Alistair. The only child of her parents, she was expected to learn the craft fairly well.
Mark Jensson is a Danish-born witch who was born to Åsmund and Frida Jensson on the 4th August 1950 in Rødovre, Denmark. He grew up in Rødovre with three brothers (Anton, Daniel and Viggo), until the age of 14, when he and his family moved to Sunrise, Louisiana for his father's work. Mark comes from a well-renowned and long standing line of magic originating in the Hovedstaden region of Denmark, it's unknown exactly how far back the line goes but it's at least 2,000 years. He is the husband of Alma Jensson and the father of Harriet, Richard, Alistair and Claudia Jensson.
Mark died when his son was 15 (and he was 45), Alistair doesn't like to talk about the details. Though he's somewhat ashamed of having such a thing, Alistair's father was always undoubtably his preferred parent, mainly because he was always a lot more understanding and encouraging of him and his other siblings than his mother, despite the opposite being the norm. He believes to this day, had his father been alive, he may not have ended up so close to falling into the dark arts as he did. Mark was extremely proud of his son's skills, having never expected him to take to the craft without so much.
Sabia Braden is a 48-year-old dark witch, born in County Kerry, Ireland on the 1st May 1968. She moved to the city of Sunrise, Louisiana to go to university somewhere where there was famously a lot of witches, and ended up staying well after. She is also the ex girlfriend (in the loosest definition of the term) of Alistair Jensson, they were together when she was 29, making Alistair 17.
During the bulk, if not the entirety, of their relationship she was manipulative and emotionally abusive toward him. Alistair failed to see this at the time due to his naïvety and age. Her sole intention with the relationship was to manipulate Alistair into performing dangerous spells for her project of the time. Whether his interest in her was mutual, as a result, is unknowable.
However, the fact that when the spell went wrong she up and left Alistair without a word of a goodbye, suggesting once he'd done what she needed of him she no longer had use for him or attachment to him, that he was essentially just a disposable tool to her.
Sabia is cold, mainly due to her extensive use of dark magic. While at the time she knew Alistair she was still in possession of some of her 'soul', after 18 years she likely far worse than she was back then (though it's impossible to know how much more dark magic she's personally done versus convinced others to do). She's continued to work on her project, and while he has no idea what it is yet, he's been keeping tabs on developments, with the help of his contacts.