Since the Thread’s firmly derailed at this point, I have no more reason to restrain myself.
For the Forsaken, Ren’dorei and other Goths of Azeroth.
Honestly, I’m not certain if we can consider the Manari skins as actual Manari Demons or just one of those ‘it was this way all along’ retcons from Blizzard, and Eredar had skin-tones ranging from greys to blues, reds and purples. Might just be the genes that expressed red melanin in the skin were also tied to other genes that gave the unlucky Eredar still trapped on Argus to survive the planetary Fel-infusion process.
We never saw any red Krokul, so maybe whatever gene is tied to that also acts as an adaptive mechanism for mutations, like what the Fel produces in most subjects. Considering the bulk of Draenei had purple, blue or gray skins, that would imply either a nocturnal lifestyle (camouflage) or that Argus had an unusually strong sun or something wrong with its ozone layer, resulting in the necessity of darker skin tones via melanin to protect against skin cancer and increase heat resistance.
More interestingly, many copper-based elements turn blue when combined with water and oxygen, and thus Draenei might have copper-based blood, resulting in their unique blue blood. Moreover, copper-based blood, known as hemocyanin, is commonly found in invertebrates and aquatic creatures, being more effective at transporting oxygen through the blood-stream and organs in low temperature, low oxygen situations. This could mean that Draenei evolved from water-based organisms in aquatic, arctic environments, and it would also explain the bulk of their males, given that in colder environments, the larger the body-mass the harder it is to freeze outright so long as the body’s core temperature remains the same.
This does cause some interesting problems once they left an aquatic environment, so we can assume that either Argus had a very low oxygen quota in the atmosphere, allowing the Draenei to out-perform rival or competing species who may have possessed more familiar hemoglobin blood-types, or perhaps the native species of Argus never incorporated iron into their cells, instead using a more abundant copper source instead. One of the reasons we have hemoglobin-based blood is theorized that life began around underseas vents, and on Earth, that translates into sulphur, zinc and iron being the more prominent metals and minerals found in samples dated to approximately this age in Earth’s progress.
It would also explain why the Draenei were this ‘Golden Age’ society. Hemocyanin is great for oxygen transferral in low oxygen density situations, but under-performs against hemoglobin in high oxygen density situations, so while the Draenei were still able to outperform rival species and predators, their energy levels would have been very low, meaning inter-species conflict would have been mostly display-based, or endurance-based, rather than the outright violence displayed by many mammalian species. This would have carried over into their evolution as from a species into a race, and we see it in Jed’hin Tournaments, where the basic move-set is grappling and head-butting, and tail-strikes and kicks are generally only permitted in high-level matches between skilled and experienced practitioners of this ‘ancient’ and ‘spiritual’ art. Furthermore, the Jed’hin restriction to be generally practiced only by males due to the necessity of having the bulk, physical endurance and the thickened cranial crests to survive the bone-shaking impacts of two massive Draenei colliding together, can possibly be traced back to old proto-societal contests for social dominance and control of the herd.
But how did they turn from sluggish quasi-aquatic creatures into the very active, intelligent and speedy people we see today?
Well … I’d argue they don’t have just hemocyanin as their blood-base. I’d argue that they also have nitrate, cobalt or sodium (salt is a metal, and I will smack somebody if I have to argue this point again!) as well as bacterial mechanisms in their lungs to help metabolise the process even further, resulting in a complicated immune system and biology, and also explain why they could jump world to world and have few issues, because their respiratory system can handle a wide range of oxygenated atmospheres with little issue as a result. High oxygen content, the nitrate/cobalt/sodium component kicks into gear and takes over. Low oxygen content, ye olde primitive copper-based part of the blood streams takes up the slack.
When we add magic on-top of all that, and the God-knows-how-long the At 'Amal Crystal was influencing their evolution, both physically and socially, I just … 
give up, I guess.
And that’s the end of my tangential ranting, carry on.
that Hunters can pull off these days. Also contrasts nicely with his skin-tone and pays a bit of homage to the lost homeland of Quel’thalas in a few places.