January 1995
As usual, Severus and Harry had a very casual Christmas at Spinner's End this year with a relaxing morning just the two of them, followed by dinner at Grimmauld Place with Sirius, Remus, and Remus's new girlfriend Nymphadora Tonks, who refused to go by her first name and only answered to Tonks. They had a much more vibrant New Year's celebration at the Burrow with more people in attendance than Severus was comfortable to be around, but it made his 14-year old son happy so he endured it. The kids spent most of the night playing a pick up game of Quidditch before they all rang in the New Year with some questionably legal fireworks courtesy of Fred and George.
They had just resumed classes after the Christmas holidays and Severus was feeling infinitely better now that he'd managed to get Harry out of that blasted Triwizard Tournament. He mentally kicked himself for not having thought of it before the first task, but it was done and now behind them.
"Oh Severus," Minerva said on the first morning before classes started back, "I see there was an official change to my house roster for a Mr. Harry Potter-Snape."
"Don't get too sentimental," Severus said realistically, "it was a means to an end."
Minerva smiled, "I guess we shall have to wait and see what the young man himself decides. I have a feeling you'll be pleasantly surprised."
The potions professor simply shook his head. No matter what anyone else thought, had Harry actually wanted to use his last name they would have changed it much sooner than this.
Severus didn't make it a habit of listening in on his son's conversations, but in Potions class that day, Ron and Harry were seated in the front row and their topic of conversation caught his attention immediately -
"Are you really going to start using Potter-Snape?" He heard Ron ask Harry once they started their work for the day, "I mean, it was all just on paper to get out of the tournament right? It's not like you're required to use it now."
Harry put down the stirring rod and turned to Ron, "I know, but technically it's magically binding, so all of my school documents automatically updated. It would be a constant battle to keep correcting professors, so I think I'm sticking with it."
Severus watched discreetly as Harry went back to stirring the potion; proud of him for keeping a close count on the clockwise and anticlockwise steps. Once the Gryffindor finished with the required three in each direction he looked back at his friend and added, "Not only that, why can't I have the same last name as my dad... Everyone else does."
Severus quickly took interest in the papers on his desk, while taking a large cleansing breath. Harry had never referred to him as "dad" before, at least not in his presence. Two things happened that day - from then on, Harry went by "Harry Potter-Snape" and he started calling Severus "dad". Severus didn't care what anyone else would say about him, but at that moment couldn't keep the smile off his face.