[quote=@Sanity43217]
I suppose it could also lead into the different races having different colours blood. Like elves have green blood, humans have red and Demons have black blood. Making identifying shapeshifter demons as easy as drawing blood. 
[/quote]
I like this, and therefore I am making this official, with a minor change.  Dwarves bleed yellow, elves bleed green, humans bleed red, and demons bleed purple.