Cup of Coffee – Remus and Harry stay up one night remembering Sirius. Slightly AU in that Harry and Remus (and the rest of the Order) are at Grimmauld Place at the beginning of HBP.
I don't know whether coffee exists in the wizarding world (judging by Ron's comments in DH it doesn't) but the story was inspired by the song 'Cup Of Coffee' by Garbage, which isn't about mourning a death, but the general atmosphere of the song fits the story. Listen to it; you might get what I mean.
Remus wasn't surprised when he saw the light flickering downstairs and the dishevelled figure with his mug of coffee clutched to him, like he was afraid to let it go. His messy hair was even messier than usual and the small patch of beard that Harry had so proudly shaved a few months earlier was left messy and unshaven. His hair obviously hadn't been cut in a long time and it hung over his eyes. Remus was almost glad he couldn't see Harry's eyes, he had seen them earlier and there was a terrifying emptiness there. Harry didn't even look up when Remus entered the kitchen and poured himself a mug of coffee, "Can't sleep?" he asked, already knowing the reply. He doubted Harry had even bothered to try to sleep. Harry shook his head, his face still hidden. Remus took a deep breath, sat down opposite Harry and mourned for the brilliant, brave boy he had known only two years previously. He hesitated before reaching out and holding Harry's arm, wishing he could do more, do anything to help. Harry stared at Remus' hand like he couldn't believe it was real.
"It's my fault," the whispered words cut through the air.
"No," replied Remus desperately, "no it's-"
"Of course it is." Harry said and Remus didn't think he had ever heard Harry sound so angry. "If I hadn't been so completely stupid as to fall for Voldemort's trick, Sirius," They both winced at the sound of the name, "Sirius wouldn't have come after me. Sirius would still be alive."
They were both silent for a long time after that and Remus desperately tried to think of what to say next, because what Harry had said was true, but he needed to help Harry realise that others had made the greater mistakes. Snape, who had been supposed to teach him Occlumency but had failed and even stopped lessons because he was angry. Dumbledore, who should have told him more instead of keeping him in the dark and everybody who should have made sure that Harry had had more options than going to the Ministry with only the DA for backup. He also needed to somehow deal with his own grief and his own angry instinct to lash out at those who could be blamed for Sirius' death.
"I don't want to do this anymore, Remus. Don't want to fight anymore. Don't want to lose anymore."
Harry sighed, "I'm being selfish. You've lost so much as well." Remus looked at Harry in surprise. Trust Harry to think of him when he was grieving.
"There's nothing selfish about what you're feeling," Remus told Harry gently, "Sirius was the nearest thing to a family you've ever had. That's a hard thing to lose. The hardest thing." Harry looked up, the picture of vulnerability, those empty eyes boring into him.
"Tell me about him. About Sirius and my dad and mum and … you. When you were kids at Hogwarts. Please." Remus nodded, momentarily lost for words, took a deep breath and plunged into the memories he usually kept safely locked away.
"Come on." Remus said, "I know where Sirius keeps – kept all the good drink. I think we're going to need it." Remus gave a small snort. "He won't mind if we drink it now." Harry nodded, gave a bitter smile and followed Remus.
"… And I think the whole school cheered when they finally started going out. I mean, Lily hadn't hated James for ages; she was just being stubborn because she couldn't admit that she'd changed her mind. Even Professor McGonagall cheered, although she'd never admit it if you asked her. So of course, Sirius decided it would be a good idea to follow them on their first date and Lily found him and decided it would also be a good idea if she hexed Sirius into oblivion. So that's how your parent's first date ended in the Hospital Wing." Harry giggled and held up the bottle of mead,
"More!" Harry shouted and Remus giggled as well.
"Did I tell you about the time we tried to get into Dumbledore's study?" Harry shook his head, then groaned and decided that shaking his head wasn't a good idea.
Harry woke the next morning feeling like his brain had been bludgeoned to death but feeling slightly more cheerful than he had before. He looked at Remus who he had been leaning on and shook him awake, "Reeeemus," he moaned.
"I've just realised something,"
"I'll write to the Prophet. This is big news." Remus muttered, clutching his head,
"No, this is important," said Harry and Remus looked at him. "There is something worth fighting for after all and I still have a family. You and Ron and Hermione and all of the Weasleys. All you lot. You're worth fighting for. You can't replace them, mum and dad and Sirius, but you're worth fighting for." Remus looked shell shocked before he grinned and hugged Harry. Harry, slightly surprised but pleased, hugged back.
They sat there for a long time nursing their hangovers. They both knew that everything wasn't magically cured now. Harry didn't think he'd ever get over his grief and guilt about Sirius' death, but it didn't look quite so desperate as it had the night before. Remus knew from bitter experience that he could survive, but it made it easier knowing he had people with him.
That didn't, however, mean they were going to survive Mrs Weasley's wrath when she found the mess they'd made of the kitchen.