It started the day Reg died, the distance. At least, amidst a war filled with grief, that was the moment in which Remus felt things changing.
They had become little more than strangers in their relationship since then. Hardly in the same place at the same time, they used their newfound distance to avoid their issues, pretend that they weren’t so viscerally unhappy. Pretend that it was possible to love someone else through such melancholy. When together, they were ghosts of their former selves. Remus missed the mischievous glint in Sirius’ eye when he was up to trouble, especially when that trouble included Remus, involved Sirius' hands or mouth on his body. But it was gone. Hollowed out by the death of his brother.
How could Remus complain? How could he compete? Compete with grief so all encompassing. Deafening. He couldn’t. So, he didn’t. He decided if he couldn’t compete, he would run, he would escape.
The wild was calling. He could escape within the wildness of others like him. He could spend hours just running, running. His joints may ache, his chest may burn, but he never ran out of empty space. Some months he recognized an ache of a different kind, the longing for a running mate, longing for the companion who had been by his side for all those years. But he pushed it away. The ache he felt when they were together hurt more than when they were apart, so he kept running.
Months later he was forced to stop. He had to come home. It was over, so he had to come home. But home wasn’t home when everyone had gone, had left him. A nagging voice reminded Remus that he had left first, left to the wild, left them alone. Left him alone.
And now, now that they were gone, there was nothing calling to him. The wild was desolate and cold, no longer a refuge for his dejected soul, and Remus was tired.
He was so tired.