Tradition

 In a nondescript booth in an ordinary pub in Muggle London sat two men on the night of July 30, 2017. On the left side of the booth sat a man with blond hair and a cheery disposition. His cheeks were flushed from drinking all night. Even though he was certainly going to pay for it in the morning, he didn't care at the moment as he drank more and more. The only other notable thing about the man was that there was something pinned to his chest right where his heart was. Upon further inspection, one could see that the pin read "Happy Birthday".

The man across from him wasn't in a much better state. His thick brown hair that always stuck up at odd angles was more unmanageable than usual. He pushed some of it away from his face, exposing his emerald eyes and part of the lightning scar that had altered his life in so many ways. He looked down at the watch on his wrist. There were only a few seconds left until midnight. 'Right on time,' he thought before clearing his throat. "Happy birthday, Neville."

"Happy birthday, Harry." said once the clock struck 12, when it was no longer his birthday. They both raised their glasses and clinked them before draining the contents, just as they had for the past 18 years. The first few times they met in this bar to celebrate together, it always turned into a contest. They mostly blamed their Gryffindor upbringings, but eventually grew out of it, preferring not to race against each other every single year.

Once Neville set his glass down, he slid one hand under his shirt to take off their shared pin. He handed it to Harry, who promptly attached it over his own heart, as was the tradition. Continuing the tradition, Neville bought the rest of the rounds for the 31st, just as Harry had bought everything on the 30th. And so, the two wizards drank, partied, and had a wonderful beginning and end to their 37th birthday, respectively. The final aspect of their nearly decades long tradition was to floo to their homes to pass out, and try to ride out their hangovers with the aid of various potions and draughts. And even though the both of them would normally regret going out like this and getting shitfaced, they would continue to do it year after year, because all was well, in the end.