"She is a bit like Mother Christmas, she is a bit more vulnerable than she has been in the past".
She added that Carla will need "family and friends more than she ever has before" due to what she's hiding.
Prior to her show exit past year, viewers saw Carla reacquainted with her father Johnny Connor and her step-brother Aidan, played by Shayne Ward, and step-sister Kate (Faye Brookes). In the past two years she has acquired a family that she didn't know she had.
"On her return to the Cobbles this Christmas, she'll really stir things up by sleeping with Daniel, Peter's half-brother", a source told The Sun.
She tried to move on by going away but Alison reveals it's family that draws her character back to Weatherfield after her brother Aidan will ask for her help to save the ailing factory.
"She has been able to switch off from the family".
Speaking about getting back into character, Alison said: "It was like pulling on an old sock or an old pair of stiletto boots!" She said: 'I got butterflies from excitement about seeing everyone, but not from nerves.
"It was so lovely, like I had never been away and I was happy I made the decision to return".
ALISON King has revealed she turned down Strictly Come Dancing.
Carla braved a dramatic time on the show and was at the front of many major storylines - enduring a battle with alcoholism, a horrific rape and a kidnap.
Producer Kate had confirmed Carla's return in October, after months of speculation on whether actress Alison would be making a comeback to the soap.
In an interview with Radio Times, Kate explained: 'It's been rumoured that Carla's coming back. "Peter will find out when Daniel starts boasting about how steamy things got between him and Carla".
"I didn't feel like I wanted to go anywhere else".