Unspoken
They were both creatures of few words. He barely mingled in human company save for a few. She often secluded herself from society.
They were both similar in many ways. If opposites do attract, then they would repel. Fortunately, they don't.
To be meeting such a frail looking girl with such fearsome powers, Hibari had been interested in her.
To be meeting such a fearsome man through Mukuro's memories, she was awed.
The most unlikely people to fall in love were brought together by an unknown entity unexplained through Science called Destiny. They do not speak to each other and they do not meet often. They do not go out on dates like normal lovers do. But they do communicate through little gestures such as a nod or a glance.
Fleeting, fragile and dangerous... this relationship of theirs. But no one knows anything for they leave it unspoken.