Red has been praised for its nobility as the colour of life. But the true colour of life is not red. Red is the colour of violence, or of life broken open, edited, and published. Or if red is indeed the colour of life, it is so only on condition that it is not seen. Once fully visible, red is the colour of life violated, and in the act of betrayal and of waste.
Alice Meynell, The Colour of Life and Other Essays on Things Seen and Heard (London: John Lane, 1896), p. 1
Red is such an interesting color to correlate with emotion, because it's on both ends of the spectrum. On one end you have happiness, falling in love, infatuation with someone, passion, all that. On the other end, you've got obsession, jealousy, danger, fear, anger and frustration.
Taylor Swift, in "Taylor Swift explains her colorful approach to writing the song Red", Daily News (November 10, 2012)