Auntie Shay was first shown briefly when Percy and Chris LaSalle busted into Marion's home during their investigation, only to find Marion and Shay throwing a birthday party for Brianne. While interrogating Marion regarding information about the drug warehouse's leader, Payton Kirk, Percy revealed Shay's criminal past, which would keep her from raising Brianne should something happen to Marion, which prompted Marion to give Percy info on Kirk.
However, Shay turned heel later in the episode, when she sold out Marion to Kirk, and as a result, Marion was shot and left for dead by Kirk during the NCIS sting. Shay's villainous betrayal was revealed when her car was discovered by Percy and NCIS at Kirk's place; as she drove from the hospital in it with Brianne. After Kirk was shot and killed attempting to prevent Percy from saving Brianne, the evil Shay attempted to make her escape, only to be stopped by Pride and the rest of the team. Shay was later arrested (off-screen) for her role in Marion's attempted murder.