As the group approached graduation, they used the Keys in the school performance of "The Tempest" to create an impressive spectacle. Fearing the impending effects of the Riffel Rule, Rendell proposed they open the Black Door to let a demon through, to use its Whispering Iron to create a key that would let them carry magic with them into adulthood. Erin was initially opposed to the idea but conceded due to her infatuation with Rendell.
The plan went awry due to the unexpected arrival of Duncan Locke, causing Luke to become infected with the demon that would be known as Dodge. After closing the Black Door, Dodge pretended to be fine when Erin asked what it felt like when the demon had hold of him. Realizing that the description was inconsistent with other accounts of possession, Erin determined that Luke was gone.
When Ellie unintentionally restored Dodge's memories, he killed Mark, kidnapped Duncan, and ordered the Keepers to bring the Omega Key and meet him at the Black Door. Though the Keepers attempted to defend themselves, they were quickly overpowered, and Kim was killed. When Dodge ordered Erin to give him the Omega Key, she told him she didn't bring it.
Dodge then used the Head Key to empty Erin's mind, scattering her memories throughout the cave. As her mind was emptied, her hair turned white, and she lost the ability to communicate clearly. Dodge was eventually killed by Ellie and Rendell, but Erin's mind remained devastated. Her few remaining memories were the existence of Dodge, the Omega Key, and Rendell, though she remained able to remember things briefly before they "go white and fade away".
Keys to the Kingdom
Erin was at some point admitted to McClellan Psychiatric Hospital. Seeing Tyler Locke and Zack Wells pass by, she was able to identify Zack as Dodge and mistook Tyler for Rendell Locke. Kinsey became curious about Erin, whose name she recognized from Mark Cho's inscription in the Drowning Cave.
Rufus Whedon was eventually admitted to McClellan Psychiatric Hospital for attacking Dodge, who was possessing the body of Bode Locke. When Rufus was attempting to escape the hospital, Erin knocked down the worker that attempted to stop him. As Rufus escaped, Erin pleaded for him to stop Dodge.
When Dodge attacked the party at the Drowning Caves, most of the students were pulled to the lower levels, except Kinsey Locke, Jamal Saturday, and Jordan Gates. Erin's memories, previously scattered throughout the cave, revealed themselves to the group, eventually hiding on Kinsey.
After capturing the group as well as Tyler Locke, Dodge attempted to take the Head Key from Kinsey to empty her mind as he did to Erin. Erin's memories revealed themselves, disabling the Shadow Key and freeing Tyler, Kinsey, and Jamal to fight back.
After Dodge's defeat, Tyler returned to the Drowning Caves to recollect Erin's memories after finally killing Dodge with the Alpha Key. Returning to McClellan, he distracted the nurse while Kinsey used the Head Key to restore Erin's mind. Erin told Kinsey how much her eyes looked like Rendell's when he was happy, and set out to go live the rest of her life.
- Locke & Key: Head Games #1, "Intermission". January 14, 2009
- Locke & Key: Crown of Shadows #2, "In The Cave". December 16, 2009
- Locke & Key: Clockworks #3, "The Tamers of the Tempest". December 14, 2012
- Locke & Key: Clockworks #4, "The Whispering Iron". February 1, 2012
- Locke & Key: Clockworks #5, "Grown-Ups". March 14, 2012
- Locke & Key: Clockworks #6, "Curtain". May 16, 2012
- Locke & Key: Keys to the Kingdom #2, "White". October 13, 2010
- Locke & Key: Omega #2, "The Soldier". December 19, 2012
- Locke & Key: Omega #1, "Our Regrets". November 14, 2012
- Locke & Key: Omega #5, "The Fall". June 5, 2013
- Locke & Key: Alpha #1, "Omega & Alpha", September 11, 2013
- Locke & Key: Alpha #2, "The End", December 18, 2013