(Warning for mentions of grooming, adult/minor relationships, domestic abuse)

The day after Juliette’s 18th birthday, Grayson brands her and officially makes her part of his Menagerie. Her birthday is February 28th, and her branding ceremony, involving the entire Menagerie, is on March 1st. It is tradition for Grayson to take each member of the Menagerie on a trip for their birthdays and their anniversary of joining the Menagerie. So, the next year, they celebrate what is actually Juliette's 19th birthday, but they celebrate it as her 20th, and then Juliette and Grayson go on their trip.

Alice, who had sex with Juliette for the first time when Juliette was 17, and Elsie, who started her relationship with Grayson when she was 16, both know the truth about Juliette's age. Dove doesn't ask, and wouldn't care if she did know. Mia, on the other hand, has a stronger moral compass than Alice and Dove and was not groomed by Grayson while she was a minor like Elsie.

So, when Elsie accidentally lets it slip to Mia that they were celebrating Juliette's 19th birthday, not her 20th, she realizes that Grayson branded Juliette the day after she turned 18. She connects the dots, understanding that this means he had a relationship with Juliette when she was underage. This is too much for Mia, who has been in a relationship with Grayson for twelve years, often being emotionally and physically abused.

When Grayson returns from his trip, Mia has cleared out the few belongings she had at his home, and schedules a meeting with him at his office. She brings her husband, and as the photographer of the Menagerie, a manila envelope containing all of the photos she's ever taken of Juliette and her permanent collar which she has cut off. She tells Grayson she's leaving him, and that as long as he never contacts her again, these are the only copies of the photos of Juliette she'll ever print. The heavy insinuation being that she would report what he'd done to Juliette.

She's haunted for many, many years about the rest of the ladies in the Menagerie, but is unable to stay because she can never see Grayson the same again.