And relations between the two species would be amicable at first, but gradually, the bodily and cultural differences between the tall people and the small people would become all too apparent, and whenever a tall person would look upon a small person, he would behold an incomparably hideous visage the like of which he had never seen before except that one time when he went to the small person village, and a small person would think the same, only in reverse.
And so it would come to pass that a state of war would exist between the tall people and the small people, and neither side would prevail over millenia, though both would possess certain advantages over the other side: for the tall people would be taller than the small people, and the small people would not only be not taller than the tall people, but not taller than some others of the small people, which is an advantage if you a small person.
But finally a lasting peace accord would be struck between the tall people and the small people. However, hatred and resentment would last between the tall people and the small people for generations, and it would only be through the enlightened activism and forward-(not to mention upward and/or downward)-looking policies of various concerned citizens in the tall and small person communities that the two would come together again. And from henceforth, they would exist in a state of enlightenment and happiness, with every community event and festival at which they attended being full of size-appropriate activities and thoughtful and sensitive acknowledgments of the tall and small people who had existed on this land before the current tall and small people.
And there would be great rejoicing.
But then, as I stood there in the supermarket, it struck me that almost everyone goes out with someone who is either taller or smaller than them, and that it's not all that remarkable really, since it would be so freakishly amazingly unlikely for a person to go out with another person who was exactly the same size as them (to within one tenth of a millimetre) that it would only happen sometimes.
So I paid my money to the supermarket guy (who by this time had been waiting for some time) and toddled off to catch the tram. Which I missed.