Cecilia was Ellen when she was young and the only friend of Herve. She attempts to save Herve after learning of his illness by praying to the fairies. She is commanded by a fairy to 'spill thyn blood' and almost dies from blood loss after slitting her wrists.
Herve was the only one with the same blood type as Cecilia and died to save her. The doctor told no one of what he had done and villagers seeing Cecilia coverd in blood suspected she'd killed Herve.
Scarecrow the half life was created by Cecilia's wishs for people to fear death and acted as her friend until she left Doolin.