At the base level of shadow society the hierarchy is simple: Survival of the fittest.
During the lower stages of evolution, it is an eat or be eaten world. Shadows at this stage are more akin to simple sentient animals. Driven by a deep need to understand and evolve, shadows will aim to grow by any means necessary. This means finding a steady source of thought fragments to feed on. This can bring them into direct conflict with other shadows ending in one party running away, consuming, or cooperating with the other. The outcome highly depends on the shadows and particular situation.
The more mature they get the more sophisticated and intelligent they become. Mature shadows can often grow quite large, and are generally composed of much more complex combinations of emotion and thought. Eventually reaching full sentience and independence, becoming similar to human beings. Just like humans they begin to create intricate networks, alliances, and tribal bonds.