Zam'im is cunning, patient and unbelievably cruel. Although it's ultimate goal is not yet clear, it too is searching for Westryn's Daughter, indicating that, while extremely powerful, the entity is not omnipotent.
Unlike Repha'im who is depicted as female, Zam'im's gender is unclear, if it even has one. In it's first appearance it appears to Robin as himself, although later it appears in the guise of a young version of Rhea. It is interesting to note that both times it appears as something Robin fears, be that fear his own darkness, or the child he tried to murder.
Its true voice seems to be comprised of hundreds of different voices speaking at once, although it often speaks with a single dominant voice, other voices can be heard to rise up. While it's primary voice is often calm, these additional voices tend to be more chaotic, deeply antagonistic, often mocking and condescending in tone. It is possible that they represent Zam'im's true thoughts at any given moment. Interestingly, although there are masculine voices present, they do tend to be overwhelmingly female.
Also of note, it's laughter is that of a child.
Zam'im makes its first notable appearance in the series finale of Salvation, however there is significant evidence that the entity has physically appeared far more frequently than originally believed. If it posesses the ability to alter it's form it could be perceived as virtually any character in the series. It is also revealed to be the source of The Whispers heard throughout the series.
Zam'im first appears to Robin following his attempted suicide and prevents him from shooting himself. It offers Robin a chance to play a game, whereby of Robin wins he will be allowed to kill himself. If he loses, he gets to continue under Zam'im's influence. In this instance Zam'im appears to be wearing the same outfit Robin is seen wearing in the Pilot Episode when he attacks Mattie. In fact, much of what Zam'im says and it's cadence appears to be nearly identical.
Zam'im's second appearance is at the very end of the series, when it officially introduces itself to Robin who has failed the game proposed earlier. It appears here as a young Rhea, dressed as she was the day of The Event.
Given that the character has the ability to alter it's form, or at least be perceived differently by different people, it is possible that it has unknowingly appeared earlier in the series.
One popular theory is that the Robin Quick that attacks Mattie in the Pilot Episode, is actually Zam'im. This would lend creedence to a number if inconsistencies in his character, as well some blatant similarities between the Pilot Version and the Robin Entity that appears in the series finale.
- Curiously, Zam'im is never actually directly referred to by name during the events of Salvation. The only connection given is in the form of a flash forward to Molly Green saying the character's name over an image of Zam'im as it appears to Robin in the previous episode. This was done to clear up confusion over whether or not Zam'im and Repha'im were the same entity.
- Zam'im shares a lot of similarities with the character of The First from the final season of Buffy the Vampire Slayer. However, in the Novel, it's ability to shapeshift is explained as only an ability to control an individual's perception, and not a physical transformation.