Disclaimer for this Overlord fanfic: This character in particular was requested by a very close friend of mine. He and I are Kadokawa Kyodai.*
Before the world Ainz Ooal Gown once knew turned into a desert, incapable of producing any form of emotional stimulation; invoked by the close bonds he felt with his fellow comrades within his guild. Those he would call his brethren that he would, formerly, be able to laugh and try with; only because no matter what happened he felt crying was definitely out of the question. Most certainly, it was definitely out of character, but one of his comrades had made an Avatar as a subordinate.
What none of the other members of Nazareth knew, including Ainz-Sama himself, was that Demiurge also had quite a few issues with the phrase "character" himself. In fact, before the finalized version of Demiurge was accepted in every detail and finally given life, his creator had trouble with how exactly to quell his Demi-Urges in order to match which subtle nuances with such a high-quality name.
What features would be worthy of realizing themselves via "Demiurge", the epitome of knowledge, wisdom, class, ELEGANCE, and unadulterated confidence; accompanied by the skills to resolve any conflict that came his way along with it.
To answer his own question, round glasses with a thin frame, a striped red business-suit, leather loafers, and the mandatory devil tail to accompany the wings, ears, and rather necessary haircut had to be included; it would be morally unacceptable if it wasn't.
The previous renditions that consisted of a skeleton in a top hat with a saxophone in his left arm and an accordion strapped on his back not only seemed redundant, there was no telling what Ainz would think of the situation. It was sadly no different than how those sitcoms used to portray scenarios of the diva when they notice the leading lady happens to be wearing the same Christmas blouse as them to the company party.
As for the next idea of a zombie holding a tobacco pipe that constantly has to reattach his left arm, because of the weight of the pipe in his hand, seemed like it would get old a little quick. Cycle after cycle, as if they were the seasons started to pass, as one "good?" idea flew by, one after another.
One of the last renditions before Demiurge was finally "Demiurge" was the same idea as the current Demiurge, but in the form of the Easter Bunny with black, white, and gray hairs; along with something else in place of the glasses he currently wears. Thick Elton John style glasses; hot pink fuzz and all, but it seemed a little barbaric for some odd reason finally resulting in the Demiurge they all knew and love today. As with all things in life, we were one step away from one of the most fearsome man-made creations to come into existence, all thanks to what would've been complacency and a slight lack of motivation. Burnout could've never ended up looking so tragic, but any other look for the Demiurge that came into existence would be nothing short of a tragedy; even if the metric was no taller than the Easter Bunny.