Ruby has been at the centre of upsetting scenes over the past few months with her long-running torment of Esther Bloom (Jazmine Franks), who recently made a suicide attempt as her life became a misery.
However, viewers will see Ruby finally confess to her role in the bullying next week as Esther's situation becomes critical in hospital.
Shaffer told PA: "Once she finds out that this is it, Esther's either going to live or die and she's in this state really because of what Ruby's done to her, that's when she feels complete guilt.
"She feels really awful and she wants to be punished."
Asked whether Ruby can show a softer side, the actress replied: "I think it's always been there, she does have a heart. We've seen how easily she was manipulated by Maddie and she wanted to be part of the cool gang.
"At the end of the day, Ruby is human and humans make mistakes. She's done an awful thing but people can be forgiven and people can change."
Hollyoaks airs weeknights at 6.30pm on Channel 4, with first look screenings at 7pm on E4.
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