Who is Maureen Malone from Cathedral and what is their importance?

Maureen Malone is Sheila's sister and an active member in the IRA. She is in love with Brian Flynn. Maureen, Brian and other IRA members unsuccessfully try to free Sheila, after which, they hide out at Whitethorn Abbey. She later leaves the IRA and her name is immediately added to the IRA's death list.

During the St. Patrick's Day activities, Maureen is taken hostage at the cathedral, where she recognizes Flynn right away. and some of the others. When Maureen and Flynn talk, she tells him that she never informed. She finds that he made a deal with Major Martin when he was captured and he wants her approval for that. When Flynn offers to free her, she refuses to go unless he comes with her. She stays by Baxter's side until the end. Maureen is at Brian's side when he dies, and she walks out of the Cathedral with Baxter.