This is Cheshire's eye, the pupil varies on the species of other Main Characters in Wonderland.
(PS: My own version of Wonderland, that is; just to clear up any possible confusion)

Basic Info:
Children in Wonderland born with this eye are destined to become main characters, though it's sort of rare. When these people destined to become Main Characters have yet to obtain the title, they are called Sub Characters; they often wear an eye patch of sorts over the eye with the simbol of a Wonderlander: a black heart.

Sub Characters are often part of the Royal Cards; or noble/royal families in simple terms. The rule in these families is that they are no longer allowed to have children while one of their offspring has the eye. In the case of twins/triplets/ect, the siblings will one day have to fight eachother to the death to ensure that only one will be able to pass on the gene.

A Sub Character becomes a Main Character when the Main Character of their Royal Card dies or is no longer able to participate in battle.

Sub Characters and Main Characters all have increased magical abilities and are the only ones known to be able to controle the Nightmares; the Bandersnatch, Jabjab Bird, and Jabberwocky.


Okay, there you go. Any questions class? This will be on your quiz next week! XD