" In the beginning? In the beginning the universe belonged to the darkness -- And then there was light. For seven hundred years, the universe was nothing but blinding white light. Then the darkness fought back and the white light was splintered.
Every sentient being born from the light now contributes to its emotional spectrum. Our state of being adds to its respective light. And it can be condensed into power.
Today, the red rage all life feels is harnessed by an ancient enemy of the guardians of the universe -- Atrocitus and his pack of red lanterns.
The orange light of avarice has been claimed, like the lives of the orange lanterns, by the obsessive and gluttonous Larfleeze.
The blinding yellow terror is wielded by the renegade Green Lantern Sinestro and his self-named corps.
The balance of the spectrum and the essential light to destroying the Black Lanterns shines in the hands of the Green Lantern Corps.
The glow of blue hope is on the verge of extinction, kept alive only by the undying faith of Saint Walker and a handful of others.
And the violet throes of love empower the Star Sapphires, who attempt to convert all to their way of being.
My tribe maintains the indigo light of compassion, which sadly remains elusive to most beings. Today, the darkness fights back again. It's begun an assault on the corps. Their homeworlds are under attack by the Black Lanterns. "

― Indigo-1, Geoff Johns (Blackest Night)