Consider the meaning of the word "fact," which comes from a root meaning something "made," something done and which exists in truth. Although some facts can be easily agreed on, such as "it is raining" (a look out the window will confirm this), these are actually a very limited number. One does not have to look so far as a presidential election to find that what one person regards as indisputable fact is a blatant lie to another.
In fact, that fact about the rain applies only if we share a frame of reference in which the water in the air seems to precipitate in a certain fashion. If we were so tiny as not to be able to perceive the raindrops, the event would hardly qualify as a fact. By the same token, if we were gigantic creatures hundreds of miles wide, a bit of moisture somewhere on our body might not even register. To say that it is raining is to register an event as being of a certain magnitude such that it engulfs our perception.
Of all potential facts, we register only a very few, which become our "faction," the totality of facts that we call reality. Political factions arise when people with similar factions join together. These mega-factions should more rightly be called "fictions" because facts diluted across multiple subjectivities quickly become divorced from the facts from which they arose.