One Way this Thing Rolls Out?

So you are reading a story. Or really a history. A narrative of a sequence of events. You understand that there are many narratives, probably as many narratives as there are stars in the sky, or grains of sand on the beach. But really, there was just one particular sequence of events that happened. One sequence, one, a series of events rolling out one particular way. You wonder if there is only one way for anything, for everything to happen. Is it true that whatever happened was the only thing that could  have happened? Did everything have to happen the way it did happen? Could one detail have been different? And if you change one detail, is it a totally different story, a different history? Is there really only one way this thing rolls out? Counter-factual - is there really such a thing as "could," or "would," or, "what if," or are these just mind-games we play?