Jess, at seventeen, is more naïve adult than typical teenager. She has been brought up to attend church and learn exorcism from her mum, and most of her interaction is with her friend Lynsey, who I don't imagine to provide her with much intellectual stimulation. Jess has a lot of confidence in her beliefs and, although she certainly isn't part of the popular crowd at her all-girls school, she would be too self-assured to be have been a victim of bullying. She is self-contained, intelligent and perhaps a little bit lonely when Giving up the Ghost begins. For Jess, the story we share with her is a coming of age and her initiation into the adult world.

Dean is probably the first boy of her age who Jess has interacted with without her mum watching from the other side of the room. He is certainly the first to have taken an open romantic interest in her and asked her out. There is no doubt that Jess fancies him back, but for the first time in her life she is forced to make a serious decision about her confidently held views. Either she must acknowledge that Dean is something sent from Satan, or that the facts of the world are far less clear cut than she thought they were. The end of the play doesn't see her rejecting her beliefs – perhaps she doesn't, entirely – but she will never stop questioning again.

I like to think that Jess's relationship with her mother is a very real one, combining the bond generated through being a tight team of two for seventeen years with the struggle as Jess begins to crave a chance to become her own person. And with Claudette's daughter Alice playing Jess, and Mary-Jo's daughter Amelia understudying the part, a lot of my work was already done for me. 

Mary was definitely the most challenging character to write, as the word 'exorcist' in itself attracts a whole host of mostly negative connotations. I didn't want her to be a hellfire and brimstone preaching, right wing stereotype, and I definitely didn't want her to be the villain of the piece, especially with Carrie developing into a more sympathetic character than previously planned. At first glance, Mary is certainly a conservative Christian, a strict mother and a harsh judge of any perceived moral deviance. But as with Dean's rock star bravado, this is very much a front. And although Dean is in many ways her polar opposite, as we get to know Mary we realise that her story in fact has many parallels with his.

We also see Mary's softer side in her relationship with Jess and, occasionally, with Carrie. Having lost her mother at a young age, she is constantly motivated by a desire to keep her daughter and younger sister safe, ostensibly from the corrupting influence of Dean, but ultimately from anything which falls outside the system of beliefs with which she cushions herself. On top of her similarities to Dean, Mary's character is made more paradoxical when we find out, despite her insistence that Jess stay away from boys, that she had her daughter at seventeen. In reality, this was written in to fit the ages of the actors – but as with Carrie/ Claudette's pregnancy, it seemed to add to rather than detract from the story.

If you think Mary's portrayal is especially convincing when you see Giving up the Ghost,you might be interested to know that actor Mary-Jo once wanted to be a nun, and brought her daughters up for many years as a single mum – just like Mary did.