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Sinead Louise O'Connor (previously Roscoe) is the daughter of Rob O'Connor, stepdaughter of Diane O'Connor and the sister of Finn O'Connor.
Arrival
Sinead befriends Amber Sharpe (Lydia Lloyd-Henry) and her father, Rob, is promoted to headmaster when they accidentally knock Mr Forsyth unconscious. Sinead's stepmother, Diane, asks Sinead to inject her with her IVF drugs and it begins to affect their relationship. Finn tells Sinead that he is worried Diane may forget about her step-children if she has a child of her own. Diane takes a pregnancy test which is negative but finds an abandoned baby at the hospital and brings him home. She tells Sinead she wants to keep him but is forced to ask Lynsey Nolan (Karen Hassan) for medical advice when he falls ill. Lynsey threatens to contact the authorities, but Anita tells Lynsey to back off. Initially unimpressed, Sinead later develops an attraction to Taylor Sharpe (Shaun Blackstock), despite distraction from Taylor's brother Arlo Davenport (Travis Yates) they begin dating. Sinead reads Amber's diary and she claims that Rob has fathered the baby she is carrying. Sinead and Diane later uncover that Finn is the father of Amber's baby and she ends her relationship with Taylor. Rob's disgruntled ex-employee, Eva Strong (Sheree Murphy), steals Amber's diary and Sinead convinces Rob to reinstate Eva in exchange for the diary. Eva, however, keeps pages and with the evidence, imprisons Rob. It is later revealed that Rob's relationship with Diane started when she was his pupil and Sinead's mother is still alive. Sinead and Ruby Button (Anna Shaffer) tease Esther Bloom (Jazmine Franks) after she pretends Sinead is her girlfriend.
Departure
Ste later proposes to Sinead and she accepts unaware that he kissed Harry twice. When at Hollyoaks High while helping Ste and Tony with a catering job Sinead almost walks in on Ste and Harry kissing but they manage to avoid her. Sinead then reads a message that Harry sent Ste and lets Ste see men on the side in the hope he'll still stick with her. However, Sinead retracts her message of Ste allowing to sleep with men due to them being two weeks into their engagement. Whilst getting ready on a night in with Ste, Sinead discovers a open packet of condoms in a bin used by Ste and Harry. Sinead later reads a text message Harry sent to Ste and discovers Ste slept with Harry. Angered, Sinead downs a glass of wine and storms out of the flat. Ste later discovers that Sinead has left the village and has taken Hannah with her. Despite Sinead's departure alongside with her daughter Hannah, Ste begins to blame Harry for all of it.