Unlike Robbie the Rabbit, this does not count as a character or a monster, but as an object Murphy Pendleton can store in his inventory as a collectible item. When the doll has been obtained, it can be observed in the extras menu of the game.
Like the Robbie toy in Homecoming, it seems to be a dark purple, with red eyes and little to no blood around the mouth. As all of the necessary items from the "Digging Up the Past" sidequest are borrowed from previous games, this Robbie seems to be taken from Homecoming along with the laser pistol, despite the description stating it is from Silent Hill 3.
Silent Hill: Homecoming
In Silent Hill: Homecoming, Alex Shepherd is required to retrieve the doll, which is stated to be a toy belonging to his brother, Joshua. When Alex asks what Joshua is doing in the hospital, Joshua says that he is looking for Robbie, which he has lost. It is here he poses as an interactive obstacle; failure to pull him correctly from a bloody hole in the wall results in Alex's arm being severed. After Alex retrieves Robbie, Joshua runs away. He makes a reappearance later as a key to opening a door. The doll is not the instigator of these events, however.
Silent Hill: Downpour
In this installment, Robbie plays the role of one of the seven collectible elements of the secondary mission "Digging Up the Past". It is outside of St. Maria's Monastery, at the end of a long staircase to the right. Like the rest of the seven objects, the Robbie doll is used to get the secret ending, "Surprise!", which is only obtainable after completing the game at least once.
Silent Hill: Book of Memories
At the main menu, enter the Konami Code (Up, Up, Down, Down, Left, Right, Left, Right, Square, Triangle, Start). A child's laughter will be heard to indicate the code has been entered correctly. The player will need to input the code each time they load up their character. If the player reloads their character, they can re-use the Konami Code to continuously get more free Robbie Dolls.