Introduction
Fortune fortune fortune. A go to explanation for phenomena that we have very little understanding of. Azure mentions a "tide of fortune" in OB and is somewhat familiar with it thanks to her experiences with the returned, Odium mentions fortune when writing his diagram review. Hoid uses fortune to be where he has to and a chromium ferring can store this attribute. Finally we have oblique mention to fortune in the curse of kind of the sleepless. Uneducated Cosmere groups consider fortune analogous to luck. More experienced ones claim it is something else.
According to the coppermind.
Though the Spiritual Realm is always how future sight works in the cosmere,[7] Fortune is not the exact same as the Spiritual Realm.[5][1] Fortune is one way of accessing the Spiritual Realm. Every time one uses Fortune, they use the Spiritual Realm, but individuals can see into the Spiritual Realm without using Fortune.[1]
From this we can know the following. Fortune is a spiritual property that everyone has(like connection or identity) and using fortune seems to make certain events occur(although given Hoid's experiences it may just make them more probable).
Some Background
Let us take a step back and look and the three realms scientifically rather then mystically. Basically lets observe what is happening on each realm when preforming a specific task. Because it is convenient I am choosing to state that the task we are observing is the creation of a sword starting at iron ore.
Most fantasy nerds are somewhat familiar with the physical process. You purify the iron or to get iron. You take that iron and add carbon(and a few other things in the right quantities) to get steel. You put that steel in the right shape to get a blade. You add a hilt and sharpen(I know more detailed and complex sets of steps exist but lets keep this simple).
What is going on in the cognitive? By my understanding each step creates a stronger and more complex cognitive image. To most humans iron ore is just dirt. Worse still it is a kind of dirt that is not particularly suited to plants or microorganisms. As such iron ore probably does not look like much on the cognitive side unless a bunch of prospectors or minors are in the area. When we identify the iron ore as useful its imprint in the cognitive side must jump dramatically. The same thing will happen when we refine it as we know have a clear, identifiable, useful item. Even laypeople will get it. As such grabbing the bead on the cognitive side will give you a nice strong impression. I don't think changing iron into steel changes the impact greatly. On the other hand the flavor must be incredibly different. The strength of the impression might not change much but its nature and maybe complexity probably will. Finally the shaping. I think here is where things get really interesting. Shallan's experience that man made objects with refined purposes have extremely strong and unique cognitive selves. A fully put together hand crafted sword has a sense of purpose. I wonder how hard soulasting a historical weapon or artifact would be?
What happens in the spiritual realm when you go through the same process? I am going to use linear time even though when speaking in the spiritual realm this is inaccurate. Everything in the spiritual realm is made out of the 16 types of investiture. Unrefined iron ore probably does not have any of Odium's or Devotion's investiture, it can't feel anything, but it certainly does have bits of Ruin's and Preservation's as it experiences both entropy and stasis. This investiture is probably heightened considerably after the ore is refined. Metal is in a highly ordered state but iron rusts away quite quickly. Also since humans are now involved bits of the investiture from the more emotional shards starts to play a role. People work with the iron so it will start to pull in some investiture from Devotion, humans use iron in business and empire so it pulls from Dominion, you hate your iron smelting job and you are pulling in some Odium. Then comes the shaping. The shape you choose also alters the type of investiture pulled. Metallic ink is used for recording and art so Endowment's investiture is possible. Ceremonial artifacts are often made from metals so Honor's investiture is pulled.
How does this relate to fortune?
My theory requires you to look at the world from the spiritual realm's perspective. I know you have been conditioned to think about the future by probabilities but for this to really make sense you are going to have to drop that. In the spiritual realm there really aren't probabilities the same way. The "future" is instead determined by the interaction of fundamental impulses. These impulses are called fortune. For example when you take refined iron and shape it into a sword you are, according to the traditional framework we use, increasing the probability that this iron will be used destructively. However at the spiritual level what you are doing is drawing a discreet and potentially measurable quantity of Ruin and Odium's fortune into the blade. The altered probability is an effect not a cause.
What this would explain.
This explains why Azure refers to fortune as a tide. Rather then some kind of cool math telling Kaladin things he is just reacting to a sudden movement of fortune rushing toward Dalinar's location. It also explains certain phenomena like evolution happening faster.
because Cultivation is present on Roshar and is leaking her kind of fortune skewing the odds of stuff happening this quickly. It also offers a rational for the curse of kinds. Bad luck does not make much sense but given Cultivation's intent is to shake things up so that things reach their full potential drawing her fortune will cause upheaval in your life especially over time. Personal and societal growth often happen during times of calamity. The curse of kind might really just be a bit of loose fortune drawn to locations. Hoid does not know why he is going to a specific place. He just follows a specific mixture of fortune that he believes will let him carry through on his mysterious goals(kind of like wayfinding). The returned get vague impressions they interpret as colors because of how weirdly placed they are relmatically and the fact they are super invested. When storing fortune scadrians think they are storing luck because the things that cause great change, meeting someone getting a job application noticed, feel lucky when in fact they are your fortune pushing you forward(your capacity to grow and change and bond). Finally atium shows you the most destructive action that you can take on short notice.
Comments are welcome I am very must still work-shopping this.