Therris is the self-proclaimed oldest of the Guardians, (even though the're quintuplets) and can be pretty sexual at times. She controls Earth and the ground.

Rain is honestly very depressed. She controls Water and Ice.

Aieru is the middle child. She is a poet, and is very imaginative.  She controls air.

Fiera is hot headed, but sly. She controls fire.

Rai is the "youngest". She likes JRPGs and Anime, and full of energy. She controls electricity. 

All in all, they can't stand each other.