Disclaimer: I own no part of the Harry Potter universe.
Dedicated to my wonderful, beloved dog Rusty, who died the day before I wrote this. For five wonderful years, he gave me his unconditional love and devotion every single day. His life was cruelly cut short by a leash and staircase railing, and my home seems empty without that energetic bundle of golden fur bounding up to greet me. Rusty, wherever you are, I love you and I miss you. This story is for you (The fact that this story centres around two men with canine alter-egos didn't register until later).
Accuracy
No-one could pinpoint the exact time when Remus and Sirius became Remus-and-Sirius, least of all Remus and Sirius themselves. They couldn't tell when an arm casually slung around the other's shoulder started meaning so much more than just friendship, or when Padfoot was elevated from Moony's pack-member to Moony's mate. The first kiss seemed natural, as did all the others that followed.
Remus never could pinpoint when he and Sirius had become Remus-and-Sirius. But he could pinpoint, with startling accuracy, the exact point in time when he'd become just Remus Lupin again. It was at eleven pm, on October 31st, 1981, when two Aurors had knocked on his door and informed him in coldly clinical tones that Lord Voldemort had just been defeated by little Harry Potter, that Lily and James Potter were dead, that Sirius Black was responsible for their deaths, and could he please come along for questioning?
Remus couldn't pinpoint which feeling was strongest - anger, shock, sorrow, disappointment or bitterness. Twelve years later, he found himself gravitating between surprise, thankfulness and happiness in the Shrieking Shack. They were Remus and Sirius again, but not Remus-and-Sirius yet.
Neither of them could put a finger on the exact time they'd become Remus-and-Sirius again; they only knew that it was at Grimmauld Place, and that it seemed as natural as the sunrise. But the sunrise is always followed by the sunset, and once again Remus found himself thinking back to the second time the unit of Remus-and-Sirius had become just Remus Lupin. He could pinpoint this moment too; when Sirius fell, his body curving in a graceful arc, his grin frozen on his face, only to disappear beyond the veil for ever. When it seemed as though an icy cold hand had closed around his heart.
Again, Remus couldn't identify which feeling was predominant, but this time it was because there were no feelings left, only numbness.