When The CW's historical drama TV series "Reign" returns in October for its third season, Mary Stuart (Adelaide Kane), Queen of Scots, will not have to face her mounting problems alone as Amy Brenneman will return as Marie de Guise, Mary's scheming mother, for an episode or more. It will be interesting to see how their relationship plays out.

The relationship between Mary and her mother hasn't always been good. Marie's last visit prompted Mary to tell her about being raped. Marie was more concerned if the rape resulted in pregnancy rather than if the attack harmed her daughter. Mary, understandably, was angered by her mother's lack of care. Mary accused her mother of using her to produce an heir to seize control.

Marie told Mary that she is ill and dying. In time, Mary's anger waned. She even insisted her mother remain in France, but the matriarch returned to Scotland to secure Mary's rule there.

We don't know what episode Marie de Guise will appear in. There is a rumor Mary may visit her mother in Scotland.

Will Marie get caught up in Catherine de Medici's (Megan Follows) revenge plot against her daughter?

In Season 2, Catherine was banned from France by her son, King Francis (Toby Regbo), because she ordered the kidnapping of her own grandson, Francis' son with Lola (Anna Popplewell). Catherine wants revenge on Mary because it was she who discovered the truth and informed Francis of his mother's scheme.

In the Season 2 finale, Catherine visited Queen Elizabeth of England, played by "Lost Girl" alum Rachel Skarsten, to ask for a favor. We know the favor has something to do with the plot against Mary.

Executive producer Laurie McCarthy revealed to Entertainment Weekly that Catherine and Elizabeth will become very close in Season 3.

"There's a guest at English court and that is Catherine de Medici," McCarthy told EW. "And that's an interesting dynamic between those two women because much like Mary, Elizabeth is someone who really was never parented. And Catherine is good at being someone's advocate and much like she was Francis' advocate, she goes over there and she strikes up a very personal alliance with Elizabeth."

McCarthy also revealed that Tom Everett Scott has joined "Reign" to play William, "a really trusted advisor/counselor" for Queen Elizabeth.

In the French Court, Greer (Celina Sinden) will find love again in Season 3 while working as a madam, according to McCarthy. McCarthy would only say that the new man is "adorable," "sexy," and, "a bad boy."

In July, E! News reported that an English nobleman will be the man to steal Greer's heart.

"Reign" returns Friday, Oct. 9 at 8 p.m. ET on The CW.

What do you think Marie de Guise's return to the show will mean for Mary? Do you think she will interrupt Catherine's revenge plot against her daughter? What do you hope will happen between the character in Season 3? Share your thoughts and theories in the comment section below.