Yeah, so every SB/RL-shipper has to write one of these, sooner or later. It maybe pathetic, but I can't help it. The guy needs some space for his own mourning, and it is only right that we squealing (or not) fangirls should provide it. Bear with it.

Silver

"In my hands
a legacy of memories,
I can hear you say my name,
I can almost see you smile,
feel the warmth of your embrace.
But there is nothing but silence now,
Around the one I loved.
Is this our farewell?"

- Our farewell, Within Temptation

There was nothing that he could say to anyone that would ease the pressure of bitten-down tears in his chest. And even though he wished that he could just weep and have it done with, there was a part of him – the part that refused to admit that Sirius truly was dead and gone – that wouldn't let the grief out of its cold silver cage. Yes, silver. Silver, because silver burnt, silver hurt, silver could break him down by its mere presence, just as Sirius was breaking him down through simply being gone.
All these nights... All these nights - and he couldn't remember how many they were anymore – when he had been laying awake in his bed, wishing for something to take him away from this bottomless hollowness that it seemed as if he was inhaling more of for every reluctant gasp of breath... All these nights made his burden of tears not cried a bit heavier.
He remembered clinging to Harry at the Department of Mysteries, just as much as to prevent himself from going after Sirius as to prevent Harry from doing it. He remembered the feeling, even now, of knowing in one moment with all his being that Sirius was alive, and knowing just as clearly in the next moment that he was gone. Like had somebody just severed a part of his very soul with a sterile, almost painless cut. The pain wasn't in losing, he knew now. The pain was in knowing that Sirius was lost. There was a difference between these two things, he knew that now.
After the memory of seeing Sirius falling through, seeing the ebony hair spread around his face like the delicate petals of a flower, seeing Sirius' eyes glitter like silver - once again Remus had been reminded of his only real weakness – in the feeble light, seeing the black veil flutter aimlessly, before once more finding rest... And hearing Harry scream, fighting him back, and as he was doing so, clutching the only anchor he had in this world, the only thing that could prevent him from letting go, let everything slide away...
After that, he couldn't remember anything. Everything went blank in his mind. He knew people must've talked to him after it, knew that he must've talked back, but in his mind, nothing but the agony he had carried inside himself existed after Sirius. There was only the short memory of seeing Harry at the station, wanting more than anything to take the boy in his arms, share his grief, but being all too crippled by his years alone and the void that now threatened to swallow him to do anything but smile bleakly and only give Harry a few words to comfort him.
And if he wished he could do more, it would hardly matter to Harry or anyone else, because no one would know it.
Letting his fingers slip over the roughness of the tree's trunk, Remus stared numbly out at the lake, now in uproar as it was whipped by the harsh summer storm. The rain was beating down heavily, and the werewolf – soaked to the skin – shivered violently, but he wasn't even aware of the cold. There was a cold that was worse than that, he knew that now.
The eternal cold of being the one doomed to live on, doomed to be the only one left, doomed to have nobody to share his laughs and tears with. The one doomed to be alone.
He grieved Lily and James, but the grief was mingled with silent acceptance.
He mourned Peter, but as much as he just wanted to forgive, he couldn't help hating him at the same time.
But the wound that losing Sirius had caused... No, it was pure. It was pain alone, pain at its deepest, pain that was so intense and perfect that it was almost unbearably beautiful, as it was slowly killing everything that was inside him.
Only the memories remained, even more vivid in his mind now, as they were laced with loss and longing and blood. Memory after memory of everything he had shared with his friends under this very tree surfaced in his mind, some of them less powerful, some of them more. One of them gripped him so tightly, refused to let go, that Remus had no choice but to close his eyes and let himself be pulled back through the years.

It had been autumn then, and the quiet inferno of the dying leaves, on the trees, whirling through the air around them, piling up on the ground at their feet, was illuminating a world that otherwise would've been dull and colourless under the slate-grey sky. He remembered nimble fingers braiding him a crown of these golden-red leaves to wear, remembered cold air that touched skin that was sensitive after the kisses that had graced it. He remembered laughter, remembered being pushed down on the wet, musty-smelling leaves, remembered feeling the cold earth against his fingertips, the softness of another human being so close to him, both in body and in soul.
He remembered eyes that mimicked, and outdid, the stormy grey sky overhead, remembered skin that would later compete with the snow in whiteness, remembered a fire that blazed stronger than the autumn forest.
"I love you, Remus."
He had looked up, eyes widening when he finally managed to understand what had been said to him.
"You... never before..."
A smile that not even the sun could best for brightness or warmth met him. "I know. That's why I am saying it now."
Yes, that had been the first time he ever heard those words from Sirius' lips, but it wouldn't be the last. Sometimes, he could wake Remus up in the middle of the night just to whisper them over and over again. He supposed he had got used to them after a while, seen them as an obvious part of his life. But right then, that autumn under that tree, they had been new and exiting and ablaze with the intensity of everything they felt as they slowly explored each other, indulged in each other.
That autumn under that tree, with the summer screaming out its death around them, these three words from Sirius' lips had been all he ever wanted.
Just as they were now.
The raindrops beating against his face suddenly mingled with salty, hot liquid, as every inner wall that kept Remus away from his grief crumbled under the onslaught of the autumn memory of these three little words. The silver cage broke, sending splinters of white-hot pain into the depths of his soul, letting a million storming, agonised feelings out of their prison cells on their way.
Silver pain, silver eyes, three words that smelled of wet leaves and earth and a sky turning silver as his senses dissolved under Sirius' kisses...
Remus cried.