This beautiful altarpiece is by the Italian Renaissance painter Carlo Crivelli. It represents the Madonna and Child enthroned with Saint Jerome and Saint Sebastian.
I think your answer should be the presidency
Magazines, the news, fashion trend websites, etc...
An audience.
This is a minimalist view, but it works as an audience can be considered to be an essential element of theatre.
Characters operate within the constraints of their circumstances. Two characters that may otherwise be friends may be turned against each other by mutually exclusive objectives or hostile circumstances. For example, Mercutio and Thibeault in "Romeo and Juliet" display similar values and would perhaps have gotten along, were they not allied with warring families.
George and Lenny in Of Mice and Men also display an interesting relationship. They are very different, but in need of one another in unique ways. They are both in difficult economic circumstances, and have disproportionate advantages (George's intellect, Lenny's strength).
The circumstances characters are in dictates, to an extent, the relationship between characters, because it dictates whether the characters offer an facilitation or obstacle to one another's objectives. Even within a play, a change in the situation and thus the calculus of the characters can change the dynamic between them.
