One thought I had the other night about the three races was how they each represent the sky in a way. I know that is pretty obvious already, but even in terms of color pie I think the flavor of these creature types is spot on.
For instance, the Soltari are primarily white mana aligned, and they represent the light that fills the sky, specifically sunlight.
The Thalakos represent the water in the air and the air itself, as in storms and tempests, being blue mana aligned.
While finally the Dauthi represent the darkness of the sky, being black mana aligned.
When put together, these three creature types result in Esper colors, which is the only three color pair other than possibly Jeskai that is most likely to have flying creatures. This provides a fascinating contrast to our other major sentient races who are found in the colors of mana that are least associated with flight (with the exception of dragons and rarely phoenixes), green and red. Additionally, green and red are the colors of mana that I would argue are most associated with the ground and or rock.
As far as the culture of the Thalakos, I could imagine it being a culture revolving around either science, magic, or both. In other words, I picture most members of Thalakos society spending their days doing something related to academic studies, such as researching weather patterns or mastering spells to control the weather, or making bigger and better humunculi.
Viashino culture might be centered around exploration, battle, and glory, with successful raiders forging powerful alliances among (thrashes? clans? another word specific to this plane for groups of Viashino?).
Just my random thoughts.
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