As a paediatric nurse, she works on a teenage cancer ward and has been known to develop close bonds with her patients. She has a tense relationship with her sister, Elise, and her mum, Joy, and had a turbulent time when she left home as a teenager herself. Marion is married to Tony but he suspects that she hasn’t been entirely honest with him about her past and is concerned about her mental health.
As the series unfolds, we learn her youth was spent with the IRA. Including her activist girlfriend.