So in biology there is the concept of parabiosis, that describes a relationship where one part experiences a positive side effect and the other one has no disadvantages because of that. The "para" shows, that only a half of the organisms experiences this advantage. Then I asked myself: Where does the "para" in parasitism come from? Is it because only one of the two sides experiences the exploitation? And if so: Is there a term for a relationship, where 2 organisms exploit each other, so basically an equivalent of parabiosis and symbiosis, but for parasitism?