Diane is a Witch and Seth Peterson's half-sister. She was almost killed after being partially mauled by Paige, a werewolf. She eventually recovered, gaining werewolf powers in addition to her magic.
She is played by Shelley Hennig.
Diana and her group of friends aren't like most kids their age. Diana, Seth, Cassie, Faye, Melissa, and Nick (now Jake , after Nick's death) make up what is known as a circle of witches and supernatural creatures. The Secret Circle is a powerful coven that consists of at least six witches and monsters or more. Although it is known that every member is born into a circle, The Secret Circle is possibly one of the most powerful covens in existence. Diana and the rest of are descendents of the Original Witch Qetsiyah.
Sixteen years ago, the former members of the Secret Circle, their parents, began to dabble in the dark arts of magic. Along their journey, an "accident" occurred which left majority of them dead. The only known survivors were Amelia Blake, Charles Meade, Dawn Chamberlain, and Ethan Conant. After the Circle was stripped of their powers, Amelia (Cassie's mother) abandoned her coven by moving to Los Angeles with her young daughter, Cassie. Determined to reunite the coven, Charles Meade killed Amelia in order to lure Cassie, back to Chance Harbor, Washington so that the Circle could be together once again.
That is where the story begins. Faye decided that it would be fun to get Cassie to use her powers by setting her car on fire. Little did she know that at that time, Cassie had no idea of her powers. Insert worried Diana and Adam and they immediately realize the cause of the fire, and the fact that Cassie knows nothing of the power inside her. After the discovery of Cassie's car accident, Diana confronts Faye Chamberlain and warns her about the dangers of their powers. The following day, Diana introduces Cassie to their coven, and tries to teach her about their families' legacy of witches. Cassie of course thinks that they are all crazy. Later that night, as Faye conjures a massive thunderstorm, Diana attempts to stop her but is struck by lighting. She then starts trying to encourage the others to join her in binding the circle as it could be dangerous otherwise, keeping the secret that once the circle is bound, members of the Circle can only do magic in pairs. The strength of the magic depends on how many members of the Circle there are.
As the weeks passed, Diana and Peter's relationship began to falter. Adam's father made it known to Diana that Adam and Cassie's relationship was written in the stars. It was predestined, and it was going to happen. No matter what Diana did, that thought kept haunting her. She knew that she would never be the girl he wants. On the night of Nick's wake, Diana went to The Boathouse Bar and Grill and broke up with Peter.
In Wake, Diana notices that Peter getting more and more upset about their breakup. The meaning of Peter's frustration isn't lost on Diana. She knows he still has feelings for her, and that he's jealous of newcomer Seth. Faye tries to warn Seth that Peter is paranoid and bad news. Ethan tells Diana that Seth and Diana have to be together. It's their destiny, but he's torn up because he still wants Diana to be happy. Diana decides to stop seeing Peter.
In Masked, Peter is still pining for Diana, and is angry at his dad for encouraging the break-up. At the party, Peter is still trying to get Diana back but she's still refusing to say yes. Diana goes off alone and is taken by the witch-hunters.
In Beneath, Faye suggests that the Circle play Truth or Dare, which results in Diana taking off her top. Peter tries once again to get back with Diana, at first they fight but ultimately end up spending the night together in a shed outside the house having sex. Diana breaks it off with Peter, saying that she needs to find herself.
In Balcoin, Melissa has returned and she has her cousin with her, a cousin whom Diana takes a liking to, which is convenient, since she and Adam are still on the outs.
In Darkness, at Diana’s, Kate Meade, Diana’s grandmother, pays a surprise visit. Diana reveals that Charles is dating Dawn (this is the cover they fed Diana to explain the time they spend together). Kate is not shocked; Charles had a crush on Dawn during their high school years. Diana leaves for school. Kate tells Charles that she is there because Diana broke up with Adam. At the abandoned house in the woods, Diana catches Adam researching dark magic and wants to know why he’s doing that. Cassie overhears Adam tell Diana about Cassie’s heritage, which makes Cassie’s anger erupt. She chokes Adam with her mind. Diana walks into Cassie’s room and discovers Cassie performing a spell. Cassie wants Jake back in town, which stuns Diana because Jake is a witch hunter. Because Jane is away, Diana wants Cassie to stay with her. Because Cassie is staying with Diana, she meets Kate. After dinner, Adam goes over to Diana’s and apologizes to Cassie. For years he told Diana everything, and old habits are hard to break. Cassie tells Diana about Kate sensing her power. Cassie did not tell Kate about the Circle. Diana tells Cassie that her grandmother is amazing and can be trusted, so Cassie should do the ceremony in the woods with Kate. Diana puts towels in the guest room for Kate. She sees items in her grandmother’s suitcase and investigates. One of the items Diana finds is mandrake root. Diana runs out of the room. Diana finds Adam and tells him about the mandrake root. Mandrake root kills witches. They rush to Cassie’s aid. Faye finds fake feathers and blood at Lee’s. Meanwhile, Diana and Adam arrive at the woods. Cassie is free. Adam and Diana find Cassie. Diana apologizes for her grandmother’s actions; she is shocked that her grandmother tried to kill Cassie. Cassie admits that she was scared; she had never felt so much fear. The fear flooded her body and erupted in a wave of power. It felt good to let the fear save her. She was scared by the power, but she liked it. Diana then asks Cassie just how powerful is she to which she looks down the window.
In Fire/Ice, Diana and Cassie waking up after the sleepover from hell that included Cassie nearly being buried alive last week. The pair playfully decide to use magic to change the color of Diana's dress, but thanks to Cassie's dark nature, the dress catches fire instead. Diana has made it clear that she is moving on. Cassie notices a symbol in the basement of the Abandoned House that she's seen in her Book of Shadows. While she's talking about this with Diana and Melissa, she realizes there's a page missing from her book. She figures out that Faye must've taken it and calls her to demand it back. Diana makes herself dance with a guy who isn't Adam, who later tells him how happy this made him and manipulates her into agreeing to give Cassie a pass to date him.
In Witness, Diana helps Adam and Cassie held in memory of Jake.
In Wolfsbane, Diana tearfully tells Seth that she trapped Erica in a tomb with a spell that neither of the two can get through. Seth is obviously angry at her and gives her until the next full moon to break the spell, or she'll suffer.
In Medallion, Diana made a speech to celebrate Adam's birthday. After the party, Cassie tells the Circle about the medallion ritual. Faye is jealous and thus reluctant, but Diana is all for it, and Melissa – stoned – is up for anything. Jake’s already in.
In Valentine, in honor of the holiday, Faye and Melissa throw a girls only anti-Valentine’s Day slumber party for themselves and fellow witches Diana and Cassie. But the night gets wilder than expected when Melissa offers Diana some mood altering “Devil’s Spirit” and the first person Diana loosens up around is Lee, who crashes the party to give Faye a present to help her improve her own power. When Melissa was "sick" by the Devil's Spirit, and instead of taking Faye's hand, she take Diana's instead.
After she manages to remove the spell trapping Erica in the tomb, she tries to apologize for what she did, saying she thought she was keeping the town safe. However, Seth doesn't listen and tells her to stay away from him and Erica.
In Crystal, Diana helps the Circle while she continues to struggle between helping them search for the crystal and her trying to fix her relationship with Seth. She tried to help Adam and Melissa by going into the mine but couldn't due the spell that keep witches with dark magic from entering. She talked to Cassie about her leaving the circle so she can be with Grant. Diana told her about her trying to get into the mine but couldn't get in. Cassie figured out that Seth is Diana's half-brother and that she is also Diana's sister.
In Traitor, Diana struggles coping with the possibility John Blackwell could be her biological father. She confronts Charles with her concerns and was suprised to discover her mother's affair with John Blackwell which Charles was unaware of. Later, while trying to find the Chamberlain crystal which had earlier been stolen, she expresses her concern to Cassie about dark magic, stating her distaste for violence and her fear of becoming like Cassie herself. Cassie reaffirms her that it doesn't feel good to kill but she does what has to be done, though Diana still persists in her efforts to prevent Cassie from killing, which she successfully manages to do before Cassie could stab the traitor witch but merely knocking him over. As they run towards the traitor witch he releases the crystal and they realize who he is, Nick.
In Prom, John Blackwell is trying to talk to Diana but she leaves along with Jake and Faye. While Cassie is at the school she sees her mother wanting to talk to Diana's mother, Elizabeth Meade. Cassie goes to Diana's house to try to convince her to go back in time to see if they can see more and see if they can see Diana's mother. Diana agrees to help Cassie. Charles asks Diana if she is going to prom and gives her Elizabeth's necklace. Charles then gives Diana a ride to school. Dawn Chamberlain is outside waiting for Charles and they discuss over John. The circle is getting ready for prom. Diana and Cassie go to Java Brew and Diana sees Grant. She tells Grant to meet her later after prom. John does a spell to make Charles think that Amelia's ghost is haunting him. The circle arrives at prom. Diana and Cassie go back in the past and see their mothers. Amelia tries to warn Elizabeth not to go to the ferry and that she knows about Diana being the other Blackwell and warns her to get out of Chance Harbor with her family. Elizabeth refuses as she sees making a peace treaty with the witch-hunters as a protection for them. Amelia then goes and sees James Conant telling him she's leaving Chance Harbor with her daughter and he tells trusting the witch-hunters is reckless. Also she tells him to tell Ethan she doesn't love him even though she does, but is putting her daughter first instead of her own needs. After they come back, Diana starts to blame Cassie that it's her fault that she brought Blackwell back into their lives and that it's his fault that her mother is dead. Diana finds out that her father killed Amelia. The circle finds Nick and try to get the crystal. Nick tells Eben he wants to trade the crystal for the demon.
After Diana showers, Seth tells her that he's going to transform tonight and asks her to keep him company, even giving her a silver knife in case he escapes. Reluctantly, she agrees.
In Family, Diana wakes up in Grant's car and he tells her that she has some text messages from her friends. She looks at her phone and realizes that Faye is in trouble and that she needs to get to the Abandoned House right away. When she arrives the Circle starts speculating about how they can get Faye back from Eben and the Witch Hunters. Cassie's phone rings and she sees it's from Faye. When she answers Eben says he will trade Faye for one crystal and that they should take it to the Boatyard where the Circle's parents died 16 years ago. Jake, Adam, and Melissa go to the boatyard. Faye is in the boat and she's scared of the guys who are handcuffing her to the same post that John Blackwell was on when they tried to kill him. Diana and Cassie go with John to a lake somewhere out in the woods near the Abandoned House. They make the crystal skull and then they realize that John is selfish and going to use the power for his own gain so they try and stop him but he knocks both of them out. They wake up in the Abandoned House and John is chanting. He turns the skull dark and he explains that he's going to kill all the other witches that aren't descended from Balcoin blood. He also tells them that there are 4 more Blackwell children coming to Chance Harbor.
The other members of the Circle start to burn but Adam is at the Abandoned House and he tries to use his solo magic from where the Circle is broken, but he is too weak and John starts beating him up and Cassie is screaming and crying, but, she and Diana can't get out of the circle of ash John put them in. That's when Cassie realizes what she must do to save Adam. She turns to Diana and starts to choke her. When Diana asks her what she's doing Cassie says "Killing You." Cassie does this to trigger Diana's dark magic. When she does it breaks the spell with the circle of ash. Cassie grabs the Crystal skull and tries to kill John with it but she's not strong enough by herself and John is about to stop her when Diana runs up and puts her hands on top of Cassie's and together they kill John. Cassie checks on Adam and they all head to Cassie's house. The entire circle is there and they all discuss binding the circle again but Diana leaves and she tells Cassie "No matter where I go, you will always be my sister, but now that I've felt the power of the dark magic I don't want to ever feel it again." She goes home and cries since Charles is dead and then she packs her bags and meets Grant at Java Brew. As she gets in the car and starts to buckle her seat belt she sees her hand and the symbol of Balcoin is on her hand. She gets scared but hides it from Grant and they start to leave. As the show is ending, you see 4 people standing on a hill overlooking the town. As they zoom in on the people you see the symbol of Balcoin on their hands also.
Physical Appearance Edit
Diana is a very beautiful girl, as illustrated in her picture. She has long, beautiful brown hair, with eyes of the same color. She's tall, standing at 5'8, has long skinny legs and is very slender, with medium sized breasts and a rather shapely behind for a woman of her age. She is slightly tanned and has rosy cheeks. When Diana smiles, she's described as "too cute to resist."