Crimson and violet.
Two colors at the opposite ends of the rainbow. One burns with passion and energy, bold and continually demanding the eye's attention. The other is passionate too, but in less volatile, softer ways. Kings and emperors use both to signify their superiority, but they always remain at either end of the spectrum.
"What are we doing?" Canada whispered. They'd gone out to the park for a walk but now he and Prussia were laying on their stomachs amid well tended grass, opposite each other and simply staring into the other's face.
Prussia pulled out a stalk of grass, brushed off the dirt, and ate the white end the roots had been attached to. "Vell…" she finally answered, "I'm currently looking into zhe prettiest eyes I've ever seen." She grinned and giggled when her lover blushed and hid his face in the grass.
Prussia was energetic, bold and absolutely shameless. She'd almost never had any doubts about herself and lived as if each day was her last (her wallet stayed inexplicably thin). Matthew was her opposite, and yet he was the same. He went about life at a quieter, steadier pace; he thought about his actions, planned ahead. Nevertheless, he too was full of energy in his own way.
After a few seconds Prussia reached out and tugged Canada's chin upwards so she could see his eyes again. They, like everything else about him, were her match. She delighted in the way only she could compliment him so perfectly.
Violet and crimson.
X3 This is probably my favorite one out of all thirty.