I think two good adjectives that describe Mary Maloney at the beginning of the story are devoted and doting. When readers are introduced to Mary Maloney, she is calmly sitting in a room waiting for her husband to get home. Her entire being yearns for Patrick to get home.
Mary Maloney was waiting for her husband to come him from work.
Now and again she would glance up at the clock, but without anxiety, merely to please herself with the thought that each minute gone by made it nearer the time when he would come.
She isn't working on something in another part of the house. She isn't out with friends. She is waiting for the moment that Patrick gets home so that she can happily see that his every need is met. When Patrick walks in through door, she greets him with a kiss, takes his coat off of his shoulders, makes him a drink and sits down near him in order to "luxuriate" in his presence.
She took his coat and hung it in the closer. Then she walked over and made the drinks, a strongish one for him, a weak one for herself; and soon she was back again in her chair with the sewing, and he in the other, opposite, holding the tall glass with both hands, rocking it so the ice cubes tinkled against the side.
She knew he didn’t want to speak much until the first drink was finished, and she, on her side, was content to sit quietly, enjoying his company after the long hours alone in the house. She loved to luxuriate in the presence of this man, and to feel-almost as a sunbather feels the sun-that warm male glow that came out of him to her when they were alone together.
Mary Maloney is a prime example of the quintessential devoted and doting wife. Of course that all changes after Patrick tells her whatever he tells her. She is stunned and not completely in control of herself. As Patrick finally crashes to the floor, Mary realizes what she has done. It's here that readers see her change from a focus on caring for Patrick to a focus on caring for herself and her unborn child.
On the other hand, what about the child? What were the laws about murderers with unborn children? Did they kill then both-mother and child? Or did they wait until the tenth month? What did they do?
Mary Maloney didn’t know. And she certainly wasn’t prepared to take a chance.
Once Mary decides to get away with the crime, readers see a new side of her. She's intelligent and cunning as shown by how she sets up an alibi for herself and convinces the investigators to eat the murder weapon.