It was not a smooth transition for the HSMC members as they did encounter quite a lot of prejudice and hate after being introduced to the school. They supported each other though, and saw each other through, bringing about real change, or at least acceptance from many by the end of the year. A harpy was even added to the group from the first years and another vampire from Aceline's year as the term progressed.
By the time Harry graduated Hogwarts, past members of the HSMC were starting to speak up and come out of the shadows with Madam Bones being their loudest proponent when she stepped forward as an aswang. Harry, Sirius, Neville, and Draco all eventually took up their seats on the Wizengamot and the tables slowly started turning in favor of creatures. As a diplomat, Harry had been concerned his seats would no longer be available to him, but after much research conducted by Hermione, she assured him that as a Potter, no one could legally keep him from them.
Almost the second he was declared innocent, Sirius Black bought a small cottage for himself on the outskirts of Hogsmeade that got lots of sun and had a huge yard for Moony on full moon nights. He enthusiastically gave Grimmauld Place to Harry and Ginny. The two compromised on Ginny decorating all the top floors with Harry taking the kitchen and the basement to do with as he wanted. No one ever entered the basement after that.
A couple years later, Harry finally figured out how to buy a very shiny ring and hand it over to Ginny without taking it back, and the wedding was the event of the year. It was just how they'd planned it when they were fifteen, down to Severus Snape singing (he was surprisingly good) with Neville and Draco providing the harmony.
Sirius never did leave Snape alone, insisting they were best friends now until the day they died.
Harry and Ginny eventually had three kids, James Sirius, Lily Ginevra and Albus Severus. It was lucky that Ginny had developed a spell to understand the dementor language since all the kids were able to speak it, understand it, and could ghost through walls and turn invisible, in addition to their fairy wings. They kept Harry and Ginny, and the entire HSMC family of babysitters busy just looking for them most days. No one really understood how this had happened since technically Jamie would be their father…but Harry and Ginny were over the moon about it regardless.
So, in addition to the normal creatures now openly attending Hogwarts, Headmaster Snape, who took over after McGonagall retired, had a student body that included dementor-fairies, eros-elves, and an extra-large gargoyle that had feathers. He complained every single Sunday when he visited Grimmauld Place for dinner, flooing in with Sirius and Remus in tow. They all knew, it was how he'd always hoped Hogwarts would be though…dementor-fairies and all.
One such Sunday, Harry looked on at his family from where he was hovering in the corner, tattered robes flowing behind him. Sirius was, not very sneakily, tying Jamie's shoelaces together where he was napping on the couch so Harry would trip later. Snape was in a discussion with Hermione over a new creature legislation she was working on.
Ron and Draco were playing chess while a group of the kids tried to give helpful suggestions that were really quite terrible. Ginny and Neville were trying to figure out what was wrong with the houseplant that Harry had accidentally killed just by walking by it, (They don't need to know that littlr detail). And Remus and Tonks were bandaging a scrape on their son, Teddy's knee from where he'd tripped while playing with his friends.
He opened the letter he had been reading again. The dementors wanted his family to visit the prison during summer vacation since they missed him and wanted to spoil their collective grandkids rotten.
Everything wasn't perfect. They still had struggles, but like in school, they all had each other. More than ever, Harry was certain that getting his soul sucked out of his body had been the best thing that had ever happened to him.
THE END