Honestly, I don't like this all that much, because it could've been better. Just a warning, this does have implications of PTSD and depression, as well as mentions of past child abuse, so please do keep that in mind. Anyway, enjoy!
Remus hated Grimmauld Place, and he hated what it was doing to Sirius. Sirius, who used to be all full of mischief and enthusiasm, a man whose grin would make Remus' heart skip a beat, someone who used to be so happy, was now reduced to a withered and emaciated form. He was merely a ghost of his former self.
Of course, twelve years in Azkaban would do that to a person, since it was a literal hell on earth. And being stuck in his own abusive household in which Sirius had sworn to never return to didn't help things either.
And Remus did try to help in any way he could, but sometimes it was all for naught.
Most of the time, when Sirius wasn't drinking or being criticised by Molly about something or other, he was in his parents' room where Sirius had let Buckbeak stay and cause as much havoc to the room as possible, to which Sirius was extremely gleeful of. Remus knew that having Buckbeak there with Sirius was comforting in a way, and he could not be any more thankful for it.
In any case, when Remus did try to help Sirius, it ended up in one of two ways; either Sirius accepting Remus' help, whatever it was, or the two of them ending up in an argument in which Sirius would eventually yell that Remus did not understand what he was going through.
Which was true, Remus didn't understand what Sirius was going through. Remus did not suffer through twelve years of Azkaban, reliving his worst memories every single day surrounded by soul-sucking monsters. Remus could leave Grimmauld Place whenever he wanted to, while Sirius was trapped there, unable to escape. Remus was not stuck in his abusive household constantly hearing his mother's screams of how she should have drowned him as a child. Remus did not walk past his father's study and remember when he was struck by an unforgivable curse.
Remus did not understand, but he could sympathise, and maybe that was what Sirius needed. That, and someone to lean on.
There were times, however, when Remus didn't know what to do. Sometimes Sirius didn't have the energy to leave the bed, sometimes he wouldn't eat, and sometimes he would just stand somewhere and stare into space. And all Remus could do was hold Sirius, and desperately try not to cry.
There were times when Remus wished this would all just end, and maybe then they would be happy.
But that was not the case. Voldemort had risen, the Order had been reformed, people already had died, and Remus was once again with the werewolf packs. It all felt the same as it was back all those years ago.
And sometimes it was all too much to handle, especially at a time like this. And Remus can see how it affected Sirius, and he couldn't help but wonder if he will ever be alright after this. But, then again, will any of them be alright? Remus sincerely hoped so.
There were times, however, when Remus didn't think so, especially when he and Sirius argued.
Yes, they argued, of course they did, because a few apologies didn't fix what they had been through, it didn't fix the secrets, the distrust, nor the many arguments they had back then.
They argued, they screamed, they swore and cried, and in the end more apologies are said, full of sincerity, and neither could deny how sorry they felt in the aftermath. It was then both of them would think about how much they wanted all this to end, and they hated how much of a recurring thought it had become.
Truly, they were living in a nightmare.
When Remus would arrive back to Grimmauld Place after days, or even weeks, Sirius would either be in the kitchen, the living room, his bedroom, or with Buckbeak—but, then again, they were truly the only places he would be, no matter the time of day.
It was late at night by the time when Remus returned, those who were staying at Grimmauld Place were already asleep. He was not surprised to see that Sirius was the only one awake, and Remus had found him in the kitchen sitting at the table, a cup of cold tea in front of him, while he was staring at the ceiling, blank-faced, as he tended to get.
Remus smiled slightly, but the worry was unmistakable in his eyes. He vanished the cold tea, and gently placed a hand on Sirius' shoulder. Sirius jumped slightly in his seat, and looked at Remus, relieved.
"You're back," Sirius said softly.
"Yes, I am," Remus replied, and moved down to place a gentle kiss on Sirius' forehead. "Let's get you to your room, shall we?"
He guided Sirius out of his seat and walked quietly to Sirius' room, which both of them had shared together. Remus helped him get dressed for bed, and rested him on the large bed in order for Remus to get out of his dirty and stinking clothes.
As Remus positioned himself down on the bed, Sirius immediately wrapped his arms around Remus' midsection. Remus let out a small smile, and allowed Sirius to bury his face in between Remus' neck and shoulder.
Sirius tended to get like this when Remus returned after days of separation; clingy, and wanting to hold Remus for as long as he could. And Remus let him, for he felt the exact same way upon his return.
Sometimes, Sirius would let tears fall from his eyes—what for, Remus didn't know—but they would fall, and Remus would hold him, stroke his hair and whisper sweet nothings into his ear. And eventually, Sirius would stop when he succumbed to slumber.
But this time, Sirius didn't cry, he merely held Remus and took him all in because he wouldn't know when he would disappear, or if he'll ever return. And Remus would to the same, he held Sirius as closely towards him as he could, and wish for him to never leave.
"Never let go," Sirius whispered, which was so quiet it was a wonder Remus heard anything at all. But he did, he will always hear Sirius.
"I won't," Remus said, his fingers carding through Sirius' hair. "Just like I know you won't."
"I will never let go, I promise," Sirius said, and tightened his hold around Remus.
It didn't take long for Sirius to fall asleep, relaxed and unguarded in Remus' presence. But Remus would remain awake, taking in his current position, and eventually fall asleep, and would only wake when Sirius had a nightmare. Then, Remus would comfort him once more.
They would do this again and again, and wouldn't know where to stop, or if they'll ever stop. But they'll keep their promises, in thick or thin, because who knows what will happen to them if they don't.
And in the end, they have each other, no matter the horrors of the outside world, or the demons within them.