Some people, Severus had heard, finished school and left it behind. They moved on with their lives and rarely, if ever, saw or heard from their former classmates. Throughout much of his school career, Severus had actually looked forward to that day, especially when it came to a certain group of Gryffindors. It was another perfect example of Severus' apparent inability to control his own life that he'd turned out to be an exception to that general rule, forced to frequently interact with people he'd prefer to wall off in his memories.
He didn't know what James Potter was doing here, but it wasn't completely unheard of for an Order member to show up at the school, even though the Order technically didn't exist anymore. Severus was somewhat painfully aware that Albus kept close tabs on the Order members and still had them perform tasks. He was, after all, the most convenient of those errand boys, thanks to his employment at Hogwarts, a seven-year-old promise, and simple proximity.
However, Severus had his own reasons to be in the headmaster's office, and he wasn't about to run away just because James Potter was there. Even if he'd rather volunteer to chaperone a Hogsmeade trip than socialize with the man.
"Potter," he said in a flat, neutral tone, hoping to depress the cheery tone and grin that were usually precursors to attempts to annoy Severus even further. "Did you have an appointment?" He sure as hell hoped not because he did, which would mean Albus had done this on purpose.