Madame Mary is the strict, but yet kindly, nanny to Saiph and Rigel. She is typically a bit of a sass, probably a hint of Saiph's attitude. But, she also acts in a motherly way towards Capella also, being it in her nature.
She's a great addition to the small family and works her best to do what she can with the job, striving to make sure Saiph and Rigel grow up to be the best kids ever.