The Aeris

The Aeris are the fundamental elements (Fire, Water, Earth and Air), and have a lot of power.

Stolen Nights
They appeared for the first time along with Suleen to judge Rhode and Lenah because What they had done with the ritual has upseted the nature. They give a choice to Lenah, either staying in the 21st century and Rhode and her could never be engaged to each other; or Lenah could be sent back to Middle Ages, and all of the crimes she committed as a vampire would be erased.

Physical appearance
Water is mentionned appearing as a whirlwind, or a liquid shield.

Fire looks like a woman.

Personnality
They are not humans, therefore they have no human desires and wish no harm to anyone.