Born 1872, baptised and registered as Darcy Monahan's daughter even though she was born 10.5 months after his death, thus making her Julien's daughter.
Julien bestowed all upon Mary Beth, all she could possibly desire, balls at First Street that rivalled any private entertainment in New Orleans. The garden walks, balustrades and fountains at First Street were all designed and laid out for her 15th birthday. At 15, she was tall and in photographs she appeared stately, serious and darkly beautiful with large black eyes with very clearly defined and beautiful eyebrows. It was said she looked more like Marguerite than Katherine.
In 1887, Julien took her to New York and then to Europe in 1888, staying for 1.5 years. In this time, New Orleans was informed by letters to friends and family that she had "married a Scottish Mayfair - an Old World Cousin" and given birth to a baby girl - Belle.
The mysterious husband died from a fall from his tower two months before the birth of Belle. Her husband, Lord Mayfair, was fictitious, they never visited Scotland. They did spend some time in Edinburgh and visted Donnelaith and purchased the castle on the hill that Petyr van Abel described in detail - the castle had been an abandoned ruin since the late 1690's. There is no record anywhere in Scotland of any Lord or Lord's Mayfair.
They returned in 1889. Mary Beth, Belle and Julien all lived together at First Street. Mary Beth loved to dance, go to parties and theatre but showed no interest in wanting another husband.
Eventually she did remarry, to Daniel McIntyre and had three children, Carlotta, Lionel and Stella.
In 1891, Mary Beth awoke screaming insisting she had to leave for Riverbend at once as her grandmother lay dying. At the moment of Marguerite's death, Katherine rose from her chair, got the Emerald necklace and gave it to Mary Beth who received it gratefully, placed it around her neck and continued to weep.
Mary Beth died in 1925. When she was dying, she was in so much pain that they gave her almost enough morphine to kill her. Stella stayed with her mother night and day, Mary Beth loved Stella dearly