Political cockroach

Someone in politics who is weak yet somehow manages to be really difficult to get rid of. They have no loyalties or convictions and will change sides at the drop of a hat. As soon as the winds of power shift, they suddenly find themselves on the other side. They often leverage their position to parasitically leach off higher powers, usually for massive amounts of money.

Examples throughout history include:
-The Eastern Client Kings of the late Roman republic (Lydia, Thracia, Pontus, Cappadocia, etc.)
-The Boyars of 15th century Wallachia
-Qatar's government

Ariobarzanes III of Cappadocia is such a political cockroach.