I actually like the idea of blue liner the best. But red over purple would darken the value, just don't know if the actual color is what you want, it'll probably look like the color of a bruise, which could be cool too. Blood is blue until oxygen hits it. So for under the skin veins blue really is the best.
I had to mention this. I'm not wanting to hurt anyones feelings, especially not Ladygrimm. I just want good information out there, and I understand that sometimes we get bad info from trusted sources, so please don't think I'm judging.
It's an urban legend that blood is blue until oxygen hits it.
Blood carries oxygen, that's its job.
Here's a more complete explanation. It will also explain why bruises are blue or purple. It's all about color perception due to light.
"Blood is a bright red in its oxygenated form (i.e., leaving the lungs), when hemoglobin is bound to oxygen to form oxyhemoglobin. It's a dark red in its deoxygenated form (i.e., returning to the lungs), when hemoglobin is bound to carbon dioxide to form carboxyhemoglobin.
Veins appear blue because light, penetrating the skin, is absorbed and reflected back to the eye. Since only the higher energy wavelengths can do this (lower energy wavelengths just don't have the *oomph*), only higher energy wavelengths are seen. And higher energy wavelengths are what we call "blue."
In an experiment, glass tubes were filled with blood and immersed in milk, milk having a similar ratio of fat, proteins, and water in emulsion as skin. At a certain depth, the tubes appeared blue.
As a phlebotomist (a person who draws blood) at the local university hospital, I drew hundreds of samples of venous blood. Almost all samples were dark red. Those that weren't were usually because people were on enriched oxygen systems.
At the same time, respiratory therapists drew blood from an artery, not a vein. These samples were characteristically bright red, unless the patient was having difficulty breathing (asthma, people with one lung, pneumonia, emphysema, whatever).
So, your veins may look blue, but even a blueblood will bleed red."
Here's my source, but google the topic of blood being blue and find others if you don't trust this website...
The Straight Dope: If blood is red why do your veins look blue?
On another note, if eyeliner pencils are proving too hard, You could use a fine-tipped brush and apply pale blue cream makeup lines, or even eyeshadow. There is a reason Ladygrimm's friend did her ink lines under the foundation, she wanted to fade and blur the harsh lines. You want a suggestion of veining, that is all.
And even though blood is red, veins look blue, so use a medium to light blue. Purple will look like a disease, and red will look like a severe infection or stryations from a massive spider bite.