Not all hesiarr live in the stable, mostly diplomatic star-faring civilization the species are most known about.

Many relentlessly cling to the ideals of the ancients, the species that were nothing less than the apex predators of all the world they knew, showing no mercy and never giving up on maintaining their status even as there were many more powerful creatures on their home world than them.

They are predatorial towards species they perceive as prey creatures, regardless of intelligence or sapience. They are also very inclined towards theft, espionage, piracy, and various other criminal activities.
These aspects, on one hand, stain the perception about the hesiarr in the eye of other inelligent species, but on the other hand, they are useful to the rest of the sepcies, as they are willing to trade stolen technology and information for other useful things, and are willing to help defend the rest of their species from dangerous enemies.
They often form groups and colonies which cooperate and trade with either the main civilization of the hesiarr, or outside entities.

The wild ones, how the more civilized hesiarr like to call them, are essentially exiled tp the outer fringes of the territories of the species, and also away from diplomatic/trade/tourist routes to other civilizations, and if they don't cause too much trouble, they are left alone. Hesiarr don't go out of their way to prosecute their own kind unless against significant threats to their civilization. Being kept away from the core worlds is enough for the main civilization to keep the direct problem at bay.

Their way of life and morals lead to colonies, and hunting groups of the wild ones' own to be fromed, which consist of multiple large ships, and well-coordinated small groups of individuals who carry out their own plans far away from any hesiarr territories, striking without warning, taking what they came for, and vanishing with their ships into the dark folds of the multiverse before any significant counterforce would apprear.