Protector

Ali is the self-appointed protector of Gianem Island.

A native to the island, yet utterly separate from its inhabitants, she walks as a ghost among them, the majority unaware of her existence.

She stalks the island, moving from village to village, observing. And when someone is stupid enough to hurt anyone of the island, her wrath is incurred. They do not live to see many more days.

Her weapon, a blowgun, filled with darts of deadly poison.
Herself, a ghost, the hand of vengeance, an angel of death.

Another idea that just popped into my head.
Enjoy.