red is the representation of the life force - the color of blood but I tell them that; that's not a good thing. Blood is only red when its not where its supposed to be. If you see red blood then that's a problem because blood is blue on the inside and where its supposed to be but turns red once the oxygen hits it.
madsci.org/posts/archives/2000-08/966430232.Gb.r.html
Why some people may think that blood can be blue is probably because of the
color of our veins, which may be visible near the skin's surface. They
appear blue because they do not get as much oxygen as the other tissues.
Red blood cells are always red. Since RBCs make up about 40-45% of our
blood, the blood is red. Red blood cells are red because they have a
protein called hemoglobin which contains iron. Iron likes to bind oxygen.
Oxygen combined with iron is red. The more oxygen iron has bound to
it, the redder it is