Black is the best and worst of colours, the source of whispered comfort and darkest thoughts.

They've always loved the night; they appreciate the anonymity it provides them. Beneath blackened skies they find peace, faces turned up toward the heavens so that they can count the stars, side by side, shoulder to shoulder on the rooftop of the tower. They appreciate the currents of the darkness and, when it is quiet, they hear it speaking to them, night breezes wrapping around them like gentle arms. Nobody bothers them beneath the night sky, leaving them to their strange rituals without comment.

From impossibly high perches they watch the city around them burn, absorbing the restless energy of a metropolis that shifts and changes daily, revelling in the information that the air brings them and asking questions of the stars. They train at night, allowing the dark to rob them of clear sight, trusting their instincts to keep them safe as they tumble and turn, allowing cool New York air and moonlight to paint their sessions in a soft sensuality that should not exist. The magic of dark sky and moonlight calls to them both, drawing them out in both their strongest and frailest of moments, singing to both the light and dark in their souls.

For Clint black is the colour of his powerlessness. Perfect darkness takes him back to the days when he was a prisoner within his own mind, able to see only what Loki wanted him to see and otherwise imprisoned in a cell of impenetrable blackness. He didn't realise how much he missed the light until it returned, how much the absence of it could rattle his nerves until it was taken from him by another and he was trapped in it. He doesn't convey it to Natasha, not when she is working so hard to make things okay again, but sometimes he wonders whether the black roots of Loki's control still creep through his brain like ivy streamers, popping the lids on old memories and forgotten fears. Clint sees things that he hasn't thought of in a lifetime, feels emotions that shake him with their intensity and he knows that the echoes of those darker days linger in him still. He sleeps with the curtains open, allowing the glow of the moon and the pollution of the street lights to offer him reassurance that he needs upon waking - that he is still himself and still in control.

In the darkest shadows of his bedroom, when the air is still and quiet, Clint convinces himself that his judgement awaits him. When he can't sleep, he waits for the doubts to resurface, for the memories to swoop down on him with black feathered wings and tear away further pieces of his soul. He waits for the calm to be ripped away, for his human face to be torn from his bones and the chilling emptiness of Loki's control to return. Though the man is worlds away and in a prison cell, Clint can feel the absence of something vital in his chest, something that was taken without his consent. No longer is he fully himself and this frightens him. He doesn't blame Natasha for the knife she keeps close, doesn't flinch from the feel of steel beneath the pillow that he now thinks of as hers, if anything he is reassured by it. He would rather she stab him in the heart than let him relive the days in which he was lost.

Natasha cloaks herself in black, it suits her history, her name, and above all her reputation. She is a woman known for her ability to kill, wraps herself in leather and darkness so that those who would pursue her will think twice. She walks the night without fear, following its call when she hears it, understanding instinctively that it is not she who is being offered up to the dark but the darkness offering itself to her. Black is negative energy, swirling, writhing within her, a poison that creeps a little further through her soul with every life she takes. Her light and dark are in balance now, her life all about controlling the impulses that were planted in her brain by men who could not control what they created. No matter how long she walks in the light, the darkness clings to her always.

With her porcelain skin, red hair and green eyes, she has the colouring of a woman who looks good in black. She uses it to her advantage, from suits to lounge wear, from evening gowns to bedding, she wears it like armour, plays up its classic connotations and uses it to hide the her reality. Natasha is a killer, that she has submitted to wear the collar of an agency like SHIELD does not change this fact. The past cannot be undone, the dead cannot be revived and their ghosts cannot be silenced. This is where she and Clint find one another - in their twisted paths and their shared history, they know each other down to the blood and bones.

More than anything else though in recent months, the black shadows and dark skies bring them reassurance. In whispered words and the consolation of fingers curling around their own they lend each other strength and convey the depth of their understanding. Words are overrated and the presence of the person they trust most is everything. They don't sleep well but when they do it is side by side, just to know that the other is there and safe, to be there if they are needed. The blackness cannot come between them because it is where they find one another, it is where the very roots of their connection lie.

For Clint and Natasha black is the best and worst of colours for it divides them and brings them together, comforts them and gives rise to their most primal fears. It is where they are trapped and where they find themselves, a source of strength and of fragility. Black undoes them and it rebuilds them, fractures them and gives them the chance to put one another back together. It is their blessing and their curse. Black is an absolute in a world that is painted in a thousand shades of grey and they love and hate it in equal measure.