Last month, show bosses announced that television newcomer Jamie Shelton had been cast as Megan's son Robbie, who will be a new bad boy character for Home Farm.
Faye told PA: "This is why she is the way she is - because she's had this skeleton in her closet.
"Now we meet him and all of a sudden you understand a bit more about her. It makes her a bit more three-dimensional."
However, Faye admitted that she is keen for Megan to stay ruthless and bitchy regardless of the storyline.
She said: "I want her to keep on her nasty path. I don't want her to go all mumsy and cosy. I don't think she will. There's evil in her yet."
Programme chiefs recently teased that Robbie's arrival will "test the loyalties of everyone around him" and spark "struggles for power".
Emmerdale airs weeknights on ITV1.