Who is Countess Eleanor Fairlie Fosco from The Woman in White and what is their importance?

Countess Eleanor Fairlie Fosco is twenty years younger than her husband, Count Fosco. She adores her husband and waits on him in dutiful, loving obedience. Cheated out of her inheritance by Laura's father, she assists her husband in cheating the fortune from Laura. She dresses in severe, dark clothing, which is the opposite of her dress in younger days, and she is described as fiercely loyal to her husband.