The sibling relationship between Declan Coyne and Fiona Coyne was introduced during the premiere of Season 9 of Degrassi: The Next Generation. Declan is very protective of Fiona, sometimes causing friction in his personal life.
Season 9In Just Can't Get Enough, Declan and Fiona transfer to Degrassi Community School and Chantay Black shows them around, but Fiona informs her that they're "boring." They meet Peter Stone and Mia Jones and invite them to their parents' posh diplomat party. Fiona also shakes her head in disbelief when Declan sets Peter up for humiliation.
In Shoot to Thrill, Declan tells Fiona he's heard rumors about her and Riley Stavros, but Fiona says she feels some type of vibe from him. Declan questions it when he hears a rumor about naked photos.
In Waiting For a Girl Like You, Declan texts her because of an emergency. She finds him sitting in front of a computer, desperate for information about Holly J. Sinclair. She gives him the information that he needs.In Heart Like Mine (2), Fiona is mad at Declan for being "Mr. High School." She tells him that she wants to be a part of Degrassi in some way. Nervously, Declan tells Fiona he'll get her an audition for the school play. Fiona is happy. When she begins singing at the audition, Declan tells her she has the part, but a few days later tells her she isn't good and Fiona is saddened.
In Keep On Loving You, Fiona visits Declan at play practice, and Declan tells her he's nervous about Holly J. because of what happened with his previous girlfriend. Chantay gets the part and Fiona becomes the costume designer for the musical instead.
in Degrassi Takes Manhattan, Declan, Holly J., Fiona, and Jane go to Manhattan together. When Fiona becomes jealous of how much time Holly J. and Declan are spending together, she decides to plot revenge. Holly J. gets mad at her and locks Fiona in a closet. Holly J. notices that Fiona is distraught and managed to get out of the copy room. She sees Fiona on the phone, realizing she's talking to Declan. He promptly shows up and Holly J. tries to defend herself, but Declan doesn't allow it, instead he quickly makes her out to be the antagonist. Walking away, Fiona gives Holly J. a taunting, knowing look. Later on, Declan sits them both down and tells them that they need to make up because he wants to spend the whole summer with the both of them.At Declan's party, Fiona drinks herself into a stupor. While, drunk she makes a scene and Holly J. tells her that her jealousy is "a little inappropriate." Fiona responds "You want inappropriate?" and kisses Declan. Everyone is shocked, and Fiona faints, using her fake unconsciousness as an excuse to avoid the consequences of her actions. Holly J. is in disbelief and tired of coming second to Fiona. She and Jane leave while Fiona secretly smirks to herself. The next day, Declan tells Fiona that she needs help with her jealousy and entitlement issues. She then breaks down, lashing out at Declan, throwing items out of her purse and calling him inconsiderate. He tells her that she's going to the Hamptons with their parents. Fiona tells Declan that she hates him in anger and he leaves her to find Holly J. and make things work with her.
In What a Girl Wants (1), Declan approves of Fiona's new boyfriend, Bobby Beckonridge. After Holly J. leaves, Fiona and Declan are officially back at Vanderbilt Prep. Declan tells Fiona he can trust Bobby because he is a family friend's son, and that he's happy for her, not knowing that he would abuse his sister.
In What a Girl Wants (2), Declan is still happy for his sister, and when they have a party, he feels bad when Tinsley's dad interrupts her for the new logo of Vanderbilt Prep. Later on, when Fiona doesn't really feel good, Declan still wants her to go to dinner with the Beckonridge's, but Fiona tells him that she still doesn't want to go, despite telling him that Bobby abuses her. Declan is still pissed and leaves Fiona to be.In Breakaway (1), Fiona is tired of Bobby, so she goes on the roof, when she receives a call from Declan. Fiona tells him that she's scared, and he tells her to get down from the roof. She does so and goes home. Declan and Bobby see the pictures Fiona took of her bruise that was enhanced with makeup. Declan tells him to stop being aggressive towards his sister, but Bobby tells Declan that Fiona is a nutcase. Fiona arrives at school, and Declan is confused when he doesn't see her black eye. She tells him that she darkened it a bit but it was true, and Declan doesn't believe her anymore. Later on, Holly J. gets a call from Declan, and they talk about Fiona—Holly J. tells Declan to trust Fiona and be there for her, like a good brother. Declan listens to Holly J. and confronts Fiona at home. Fiona shows him bruises on her legs from Bobby, Declan tells her that he believes her.
In Try Honesty (1), Fiona pretends to meet Holly J. at the Dot, but fools her and she sees Declan there instead. Fiona explains to Holly J. how Tinsley is the slut, and that Declan probably won't cheat on her. Holly J. and Declan sit at The Dot and talk. Declan tells her how he didn't want her to go to Manhattan on the trip because he and Fiona planned for him to come visit.
In Try Honesty (2), At school, Holly J. and Fiona talk about how the whole thing was a big misunderstanding, and how Declan is back and everything is okay. Later, Fiona is Holly J.'s first customer at her new job, and she informs Holly J. that Declan is heartbroken over their break up.In Love Lockdown (1), Declan and Fiona are walking to Degrassi, while discussing why Declan came back. Fiona discovers from him that his intentions were to see Holly J. again. Spotting Holly J. editing the sign outside of the school, they say hello and she surprised to see Declan. Before the awards, Fiona fixes his tie, and he asks her why she waited so long to tell him about Holly J. and Save . Fiona reveals that she didn't tell him because she didn't want to ruin the holidays. Fiona and Declan sit next to Holly J. and Sav at the awards. Afterward, Declan has a party at Fiona's apartment and everyone is there having a good time. Declan expresses his love to Holly J. when he gets her alone, and she turns him down. Declan expresses his feelings to Fiona, who purposefully gets extremely drunk so that Holly J. would stay the night to help take care of her, giving Declan a chance to make amends with her. This plan works, and Declan and Holly J. end up having sex.
In Love Lockdown (2), the next morning after the party, Declan is making breakfast and is greeted by Fiona. He tells her that he and Holly J. are "officially" a couple again. He also announces that he'll be enrolling back to Degrassi. Declan is later seen outside of Degrassi. He sees Fiona and he tells her that he thinks Holly J. is avoiding him, and he is unsure why. They then spot Sav, and Declan tells Sav that if he sees Holly J., he should tell her to give him a call. When Fiona gets home from school, Declan is excited and asks Fiona what Holly J. told her. Fiona is hesitant, but then confesses that Holly J. didn't want to have sex with him last night, and that she felt pressured to do it with him. Later, Fiona gives Holly J. a letter from Declan, and tells her that he is leaving in a few hours.
In Cry Me A River (2), when Fiona is given the role of director for the school play, she says 'Oh, I'm not like my brother", referring to Declan.
In U Don’t Know (1), Fiona mentions how in the Christmas of 1993, their mother took about "1,000 pictures" of her and Declan surrounded by baby gifts.
Mrs. Dawes also mentions that the drama class is intimidated since she's Declan's sister.
- They were born in December 1993.
- They both had romantic feelings and kissed Holly J. Sinclair, but only Declan had a relationship with her.
- They both directed a school play- Declan directed Space Awakening in Season 9 and Fiona directed Love Roulette in Season 11.
- They are the second set of twins on Degrassi. The first were the Farrells, Erica and Heather, the third were Anderssons, Bo and Ingvar, the fourth are the Bakers, Luke and Becky, and the fifth are the Hollingsworths, Frankie and Hunter.
- They are the first set of twins of the opposite gender, the second set are the Bakers, Luke and Becky and the third are the Hollingsworths, Frankie and Hunter.
- Fiona kissed Declan to make Holly J. jealous.
- It is rumored that Degrassi originally intended for them to have an incestuous relationship but they were restrained.
- They were seen in the Season 9 and 10 opening credits together.
- Neither was seen graduating with the Class of 2011: Declan moved and Fiona was held back.
- Declan didn't attend Fiona's graduation.
- Declan shares the line "I like people." with Fiona's ex-girlfriend Imogen Moreno.
- They were both the unrequited crush of a friend.
- Fiona appeared in more episodes than Declan.
- Fiona appeared in 96 episodes, while Declan appeared in 26 episodes.
- They both made their first appearances in Just Can't Get Enough.
- They were both members of the Degrassi Drama Department.
- In Just Can't Get Enough, Peter mistakenly believed that Fiona was Declan's girlfriend.
- In Waiting for a Girl Like You, it was revealed that Declan was born before Fiona, making Fiona the youngest twin.
- Declan: "All our lives we've only had each other, but that has to change!"
Fiona: "Is that why you've been excluding me ever since we got here? You're all I have, Declan."
Declan: "I CAN'T be, Fiona! I'm scared that you're messed up, and I can't help you." - Degrassi Takes Manhattan