Marcie Millar is the easy and popular girl at Coldwater High School who has an on-going grudge with Nora. Marcie and Nora have been enemies since middle school, when Marcie publicly displayed Nora's underwear and spray-painted 'whore' on her locker. The reasons for her hatred of Nora are unknown until the 2nd book, Crescendo. Her dad is the owner of Coldwater's Toyota dealership and she lives in an affluent neighborhood.
In Hush, Hush, Marcie is first shown when she is in CHS's school library. She insults Vee calling her "Supersize". She is later shown at a library again when she and Nora get into a Verbal fight that has to be broken up by security. She is attacked by Jules that later that night.
In Crescendo, Marcie is Nora's summer school Chemistry partner. She invites Nora to her summer party, there Nora steals her diary. When Nora returns it, Marcie reveals why she hates Nora. She is dating Patch for the majority of the book
In Silence, Hank and Susanna Millar get divorced. Hank starts to date Blythe, Nora's mom. When she catches them at a dinner together, she starts to cause a scene. When she follows Nora to the restaurant bathroom she seeks Nora's help in getting back a necklace Patch supposedly gave her during the summer. She also takes Nora dress shopping for the Homecoming dance.
In Finale, Marcie is dealing with the loss of her dad. Saying that her and her mom need a break from each other, she forcefully moves in with Nora and her mom. There she spies on Nora and tries to learn her agenda. To help with this, she tries to spend time with Nora and her mother. She also wants to find out who killed her father. When she finds out it was Nora who killed him she burned every Fallen Angel feather that Nora got from Pepper Friberg, including Patch's, sending him to hell. In the Epilogue, it is said that Marcie died and lasted longer than expected, and that only 5 people went to her funeral.
Marcie is conceited, vain, vindictive, and is only interested in using people if it suits her best interest. She is a backstabber, dramatic, and manipulative.