"It's me....I've been trying to reach you for so long..." -Mariah when finally awoken.Mariah Smith is the sister of Jerry Smith, known by his nickname Yellow Guy, who was murdered by Purple Guy after he forced Jerry to kill people he wanted dead. Mariah appears as a young woman with brown hair, hazel eyes, a red t-shirt, and jeans.
Mariah was an engineer at Fredbear's, like her brother, but was used as collateral by Purple to force Jerry into killing specific targets for him. She was caught by him and murdered, detailed in this book. Mariah was stuffed into Clarissa, and part of her soul left the animatronic body, eventually haunting a broken prized possession of the Smiths; a plate, inherited from generations. The way the plate works is, if you can assemble the pieces back into one, you can talk to Mariah, otherwise her sentences are short and staticky.
Mariah was once a happy, care-free woman; some of these traits still show, but mostly she is happy just to see her brother again by haunting the shards of the plate.
Springtrap: Her relationship with him is a weird one, similar to Clarissa's; she used to love him before Purple was inside him, but when remodeled into Springtrap 2.0, she felt love for him again despite his past with Purple.
The Chef: The two get along well; Mariah often talks with him while he is making something, even if it's guard pizza.
System X: X has said he would try getting Mariah a body to control, so she and Yellow are grateful for trying to help.
-In Five Nights At The Inventory 3, Mariah is seen on your desk in Office 1, with the shards in a jumble so she is silenced. Reasons are unknown.
-Strangely, the pieces of the plate fall apart if attempted to be put together. A theory is Mariah's soul is somehow preventing this from working.
-Clarissa and Mariah are technically the same person, but they try to differ themselves from each other; both consider Yellow a brother, however.
-The plate is made up of three shards; in the future, the pieces will be split more.