So Mary is really Muriel – an Angel – well actually an Archangel:
Muriel means “Perfume of God.” This is a female archangel who brings peace and harmony to one’s life. She is responsible for carrying around the message of peace and harmony to people on the Earth.
Her angelic responsibilities also include tending the plants and animals on this Earth.
Depicted with a crown made of flowers, it is known that when she is in your presence, you will smell the scent of your favorite flower. When this happens, it will confirm that Archangel Muriel is somewhere near you. [https://www.guardian-angel-reading.com/blog-of-the-angels/archangel-muriel/]
But now she is on Earth after her wings have been removed by demons, she is not quite as peaceful as before – at least when it comes to fighting demons.
She is also not quite au fait with human behaviour and norms and speech. Which gives a lighter touch to this novel which could otherwise be rather dark as is it mostly about the fights she gets into when dealing with possessed humans.
Erin writes a good story and this is a good series of novels about Muriel and how she adapts to her new life and new companions.