Mass Effect - Rebirth
The pirates and slavers banding together under the banner of Black Star were doing so out of dire necessity. The scum of the Terminus systems used to prey on the rest of the galaxy, raiding systems in the Attican Traverse or, if particularly gutsy, deeper into Alliance or Citadel space, only to slink back to the safety of the Omega nebula. With the relay down, however, the easy pickings were gone, the food, water, and other basic supplies were drying up, and desperation was setting in.
Black Star was, until recently, a minor mercenary company. They had some minor contracts with Thunawanuro and Logasiri, they ran drugs, did some artifact smuggling through Citadel space, some minor gun-running and corporate wars-for-hire. When the relay went down, they had the cleverness to realize that there would soon be a lot of desperate pirates in need of the food and supplies their contracts could provide. Black Star started recruiting.
It rapidly became an enormous outfit with a reputation for the worst sorts of villainy. Their allegiances shifted, what with their shifting demographics. Their largest single employer and financial backer became the colony of Logasiri, who used them as a proxy-military in their aggression against the colony of Lorek. As the politics of the nebula settled out after the relay went down, Black Star became the natural rival and antagonist for Red Dawn, each becoming, in their own way, a proxy-military for the Lorek / Logasiri dispute. Red Dawn had better organization, but Black Star had numbers and desperation.
Ultimately, Black Star went too far, seizing and blockading the planet of Thunawanuro, thereby effectively seeing to starve the entire nebula into submission. This united the various factions who had previously remained neutral, and an immense allied force under the command of temporary “warlord” Aria T’Loak, crushed the Black Star fleet over Thunawanuro. Simultaneous Black Star attacks on Omega, Imorkan, and the Sahrabarik relay were also repulsed. This crushing, demoralizing defeat has splintered Black Star back into rival, squabbling pirate gangs, and its ability to threaten the entire nebula is no more.