The Norn… those immensely poweful beings who control even aspects of fate for the gods. What is most interesting is that the three spin the Web of Wyrd concurrently, meaning that past, present, and future occur simultaneously. As such, there is no definitive future and even your past is open to change by means of retrospective reinterpretation.
The easiest way to understand the action of the Norn is to think of them as a team of scriptwriters: one is responsible for your backstory, one is outlining the future plot arcs, and the other is writing the detail of each scene as it occurs. You only experience the detail of your current scene — time as you experience events in what you perceive to be ‘now’. Your backstory can be re-written at any point and your future plotline can be re-written at will, before you experience it. As such, there is no fixed fate for the majority. Only those ‘major characters’ are worthy of the attentions of the Norn and significant enought to warrant a fixed plotline from which nothing can deviate. For the majority of those incarnate as humans, the reality is that they are insignificant characters — merely ‘extras’ in a scene within the story. To think that every aspect of every life is pre-determined is arrogance. Some are just not that important.