Disclaimer: Remus, Sirius and Sirius' laughter all belong to Ms. J. K. Rowling
Laughter
There were many things that Remus Lupin loved about Sirius. The inky blackness of his hair, and the lights that danced in his eyes when he'd thought of something particularly devious. Sirius' intellect. His rare, but sparkling moments of incredible kindness. His six-year-old-on-sherbet madness that skipped, joyous and bounding through everything he ever did.
His laugh.
God in Heaven, there was no other sound like Sirius' laugh.
It was a cackle, a howl, a roar, a phonetic rendition of everything wicked and mischievous in the world. It was nothing less than the sound of his carefree soul. Sirius never laughed half-heartedly. There was no middle ground, and making him laugh warmed you up in a way fires on cold days or whiskey in the Three Broomsticks never quite did.
Remus lived for that laugh and Sirius went and ruined it.
He hadn't heard it of course. He hadn't seen Sirius that day they'd died. He'd only learnt from other people. Sirius had laughed.
He'd laughed.
The man who had struck down his best friend, murdered weak, pitiful little Peter Pettigrew and twelve innocent Muggles had thrown back his head and laughed.
Remus could still hear it, bouncing around in his head. He had lived for that laugh. Peter had died to it.
It haunted him, in every memory, in every dream, in every terrible joke cracked and every giggling gang. He came to hate it.
Even now, when all was forgiven but never forgotten, he still flinched. Azkaban had eaten away Sirius' soul and his laughter. No longer carefree, no longer beautiful, it hung on the air like something awful. Strains of Black madness.
"Come on, you can do better than that!" He was laughing at her.
Laughing at Bellatrix Lestrange.
Laughing like he hadn't laughed for fifteen long years. It was a cackle, it was a howl and a roar and the phonetic rendition of everything wicked and mischievous in the world.
And it had warmed Remus' heart.