Vilani and Vargr said:p.42, attempted paraphrase:
In the manner, form, or style in which humans feel a primary pull of loyalty to one main peer group, vargr is capable of feeling equal pulls to community membership in many packs. Many commitments means safety.
In the manner, form, or style in which humans have many goals, vargr have one goal: Charisma. All manner of risks are acceptable to serve Charisma.
pp.46+, The Vargr Extents
The degree of control exercised by the central government is far more tenuous than that found within the Imperial region. (I'll have to remember that)
My Theory:
The Empire of Varroerth, typical of Vargr empires, is more like a "king of the hill" vehicle for Charisma than anything else, and in its nearly 1,100 years of existence it has not only changed hands, but frequently changed capitals and wide swaths of border. In a certain sense the empire may more resemble a nation in constant civil war, where the regional governors periodically "march to the Capital" (whichever world is currently the titular capital, that is) and fight it out, fleet to fleet, perhaps ending with a duel. The empire is large enough to attract all sorts of fleets, as well: if a popular leader in Tuglikki, Provence, Dhuerorrg, Knaeleng, Fa Dzaets, or Ngathksirz Sector wants to get a proper shot of Ultimate Charisma, then he may fly his fleet into to Varroerth and try to take the throne.