Analysis of information sources in references of the Wikipedia article "Parasites in fiction" in English language version.
Parasites, in a phrase, are predators that eat prey in units of less than one. Tolerable parasites are those that have evolved to ensure their own survival and reproduction but at the same time with minimum pain and cost to the host.
A satirist seeking to portray client misery naturally focuses on the relationship with the greatest dependency, that in which a client gets his food from his patron, and for this the prefabricated persona of the parasite proved itself extremely useful.