There's just something about the color red in the human psyche. It's the lowest visible color on the human color spectrum. It's the color of blood
and therefore danger and warnings. But it is also the color we associate with fire,
and therefore power, warmth, love and passion (and sometimes evil), and is a popular color in flags and heraldry. Much unlike pink
, red can be seen as a very masculine color, if not more than blue. However, it's also a common color for mature, seductive
ladies. If a language has only three primary color terms, they will invariably be black, white, and red.
Therefore this is an index of tropes involving the color red.