Choose A and B. Then choose P and Q at random, then draw lines AP and BQ. This is equivalent to choosing a random direction (since the union of all rays leading from a point is the whole plane, and every ray has the same number of points, uncountably infinite.)
As the problem stated, disregard the functionally impossible case that AP and BQ are parallel, or that their intersection, X, equals any of the other four points.
Place points P' and Q' on AP and BQ respectively, such that A is between P and P' and B is between Q and Q'. Now rays AP and AP' are opposites and each has a 1/2 probability of being chosen, and exactly one of them contains X. Rays BQ and BQ' also each have a 1/2 probability, and exactly one of those contains X. If both rays that contain X are chosen, they intersect, but if not, they do not. The probability of this happening is (1/2)*(1/2) = 1/4.