Vermillion
Vermillion is not the right colour to describe blood with, he knows, but its four syllables make it a pain to pronounce. Obviously, it's a pain to remember blood - his most vivid memory of it being the splashes of hers and Orange's (he cares nothing for Orange, but there was a ton of his blood there, too).
It is also the colour of the explosions in the far, far distance on Earth, the ones that discolour the heavenly blues of the skies and rid the birds of their habitats.
Vermillion is the colour of bloodshed and destruction, an everlasting sight.