A young Jedi woman by the name of Luvree Huchess came across the Dark Side when she was on a mission on the icy planet of Hoth. There she ran into a battle between two Sith in the snowy tundra. Instead of staying away from such a clash of Dark Side, it intrigued her. She could feel the Dark Side pulsing from their angry silhouettes and it tasted wonderfully to her.
Eventually, Luvree decided to research the Dark Side in secret in the Jedi Archives. She saw how powerful one could be with the use of the Dark Side, and she instantly fell in love. However, with her new found passion, she didn't know what to do with it.
One day, while on a mission with a fellow Jedi Knight, Luvree attacked her for no reason and murdered her. The urge just came to Luvree and she acted on it. The sound of the Jedi's screams and agony, the smell of singed blood from her lightsaber blade, it excited her, and so she decided that this is what she wanted to do.
She took the ship they came in and never returned to Tython. Luvree renamed herself to Imorra and started a new life. She knew exactly who to find to train her in the art of the Dark Side. Another Fallen Jedi by the name of U'pruh Cue-Del fell away from the Jedi Order to learn about the Dark Side as well, and Imorra found him on Geonosis. After a couple of years, she became quite strong in the Dark Side, and murdered U'pruh when she felt she no longer needed him.
Then, it was time for recruiting. Imorra remembered there were a few suspicious Jedi back when she was a part of the Order and decided to track them down. After a year, she had 6 members and called themselves the Shadowblood Sisters.
They found whatever trouble they can muster for both the Sith and the Jedi; for both the Empire and the Republic.
Their demise was all thanks to the Sith Sorceress Melodica, who later became Darth Xerska. Only one survivor was left, Wes, who somehow escaped the eye of the murderous Melodica.
Wes eventually met a young bounty hunter and they helped make a bounty hunter guild named the Shadowblood Guild.