Myst Guardian

What they are
A Myst Guardian is someone who takes on the role of protecting one confirmed being unable to protect him/herself. They become shells, as a living being is not able to contain the power of being a Myst Guardian.

Yukiko was a Myst Guardian, having been confirmed to Shana; the Flaming - Haired Burning - Eyed Assassin at birth, and the form Shana grew up with had been a shell of her actuality. After seeing her shell (She did not know it was a shell) fade away, Shana took on the role of a Myst Guardian, realizing that Yukiko had died at birth, living with the reality that she herself was then a shell.

Myst Guardians are rare, and their shell fades away when their main goal is accomplished. Everyone's minds are erased of any memory with that Guardian, while only the confirmed being remembers, and those who knew s/he was a Guardian. Too many people knowing could result in fatal burning out of the Mystery Guardian.

In Shana's case, her mother knew, and Cole; Aeron, Shiro; the Snow - Haired Icy - Eyed Specialist, Kin, Mizu, Yami, Yuudai, Shinya; the Flaming - Haired Burning - Eyed Assassin also. In Yukiko's case, only Shana remembered, of all the people in the world.

What they can do
A Myst Guardian is given a special way to guard their confirmed being.

In the book The Lord's Gate, Shana revealed that she was a Myst Guardian, and realized, finally, that she actually had two beings. Shana's specialty had been brute force, having chosen it when she was confirmed, and hating being as weak as she was, even needing a Myst Guardian.