EastEnders star Diane Parish says her character Denise Fox will feel "absolute terror" when she sees her ex-husband, serial killer Lucas Johnson (Don Gilet), back in Albert Square, but she's "shocked and betrayed" to see her daughter, Chelsea, with him.
Parish said Denise is worried about Chelsea's behaviour: "She should be really thrilled and happy to see her daughter, who she hasn’t seen on Christmas Day in a while, so that is a lovely thing, but she shouldn’t have been standing next to her murdering father."
Her anxiety is hardly surprising: Lucas was jailed in 2016 after he imprisoned Denise in their basement and tried to pin his murder spree on her. In the meantime, Denise has been bringing up her biological son, Raymond, after his adoptive parents died in a car crash.
Chelsea, meanwhile, departed from Albert Square for Spain in 2010, but subsequent phone calls revealed the reason she'd stayed away was her deep shame at her family.
Chelsea's return brings "peril" with it, according to Parish.
She said: "It was one of the most interesting relationships I have ever had on EastEnders and I think it has now gone into another dimension with Zaraah [Abrahams, the new actor playing Chelsea]. It’s now two women at loggerheads, rather than a teenager or young girl, mother vs daughter so that will be interesting to play through."
While Parish is delighted to have her "mate" Gilet back as Lucas, she is worried for Denise.
"Don is just the most surprising and fantastic actor, he literally lets Lucas seep into his veins, and you watch it happen. I don’t know what is in his mind but you see something change in his eyes. The light in his eyes goes dead, it is quietly terrifying but really good!"
EastEnders' executive producer Jon Sen explained how the return of Chelsea and Lucas would affect the family.
"The fact that Chelsea has kept contact with Lucas causes a huge sense of betrayal and fractures the family because of everything that Lucas did when he was last on the Square. Denise really struggles with reconciling the daughter she knows with the ex-husband that treated her so terribly."
Abrahams, who has taken over the role of Chelsea from Tiana Benjamin, hinted how things will play out: "She ends up being back on the Square with her dad because he has been released out of prison. She is wanting to forgive him for all that he’s done and she believes that he has changed. Whether he has or not – we shall see. I think Chelsea might have a few of her dad's traits. They’re not the duo you expect."
EastEnders screens at 9.05pm on BBC One on Christmas Day.