Considering a Three Way
In the play Oedipus Rex by Sophocles, a certain story from Oedipus’s past is told on two occasions. The story concerns the decisive moment when Oedipus, fleeing his hometown in order to avoid an evil prophecy, kills a man at ‘a place where three roads meet.’ 
It turns out of course that the man he kills is his father (whom he had never met), which is one part of the very prophecy that he was trying to prevent. You cannot escape your fate. What, though, is a place where three roads meet? If we are literal about it, any place where two roads meet is also a place where three roads meet, as long as one of the two roads ends at that point. (If we want to describe a place where two roads meet and neither one ends at that point, then we simply have a four-way crossroads.) We could conceive of three separate and independent roads which all converge at a single point, but the de facto experience of any such point is that it is a place where the road from x to y hits the road that leads off to z; in other words, we experience it as two roads. I have tried to find a place where three roads meet as equals, so to speak, and have failed; if you know of one, please send in a comment below!
It is not by accident that such a place is chosen for this unnatural act, as the play makes clear that whatever path they choose in life, the three main protagonists – Oedipus, his father and his mother – are fated to collide along the way. The strange power of the number 3 crops up in several places elsewhere in the play. The other part of the prophecy that Oedipus is haunted by is that he will sleep with his mother, and this also turns out to be true. The place where the three roads meet is a kind of topographical model for this incestuous collision, where what ought to be separate is mixed, where two-ness is polluted by three-ness in something much worse and more powerful than a love triangle.
The awfulness does not stop there, however. The implications of the tale can be generalised, as we know from Freud. Topographically speaking, all intersections of two roads, of two people, become an intersection of three. (If they pass through each other but do not join, then we’re back to our four-way crossroads). All sex is incestuous, all violence is against fathers, and there’s not a damn thing we can do about it. Merely to live and to intersect with others means that we will pass through these points, which makes them highly charged, special and totally banal.