The Blood Pack appears to be loosely organized, with various independent companies run by krogan battlemasters. Krogan are clearly the leaders of the organization, with vorcha serving as little more than cannon fodder. Certain krogan clans, including Clan Weyrloc, appear to be closely associated with the Blood Pack.
When the Reaper invasion began, krogan began returning to Tuchanka in large numbers, turning control of the Blood Pack largely over to the vorcha.
The Blood Pack are a significant force in the poorly governed Terminus Systems, but their forces are far too limited to threaten a major planetary government, let alone an interstellar government.