Hey man, nice to meet you too and thanks so much for taking time to look trough my gallery. The game and anime references you mention are also favourites of mine. I can also definitely see the similarites with the women you mention, although I've just been drawing from photos of random girls pretty much :D
But on to the fanart at hand. Glad you like the scorpio. I'd love to draw it in the demon halls, but before I consider that I'll have to spend a long time thinking how the place would look and the designing it. Hopefully I'll get to that though.
It's really cool to me all the different ways a single piece of pixel art can be interpreted. I've always seen scorpio as having two red eyes, but when I started drawing that it looked like every other generic monster with angry red eyes so I tried to spice it up with that big eye :D
In terms of the colors here, check this link to see some orange versions: http://sta.sh/0xoag1timk0 Tell me what you think.
Without getting too technical, there's a theory called color theory. And one of it's basic laws is that each color has a complimentary color. Meaning that each color looks the best next to another specific color. For example green + red, orange + cyan/light blue, yellow + purple, etc.
Taking that in consideration I'll try to lay out my argumentation. The first example of orange and purple is kind of gross looking. I think the combination will look ok the other way around, but the point is to see the scorpio orange :D
The second one with cyan is a bit better, they are complimentary colors, but the color is kind of weird for a demonic eye isn't it. It doesn't really communicate "demonic" or "evil". When I see this color I usually get reminded of hospital nurses and surgeons.
And the third one, the yellow is also working ok with the orange, but the two colors are very close to eachother and the eye just doesn't stand out as much. The same thing would happen if I combine orange with red, because they are also close colors. Usually sameness in colors is boring. Contrast is what creates interest, but it has to be the right contrast.
That being said, the orange + yellow is the best compromise out of the three in my opinion.