He might meet Mavis first. Since she's often quite curious and adventurous, she could be the one to come across Harry when he arrives at the hotel. She would probably be very interested in this new visitor who has a different kind of magic than what she's used to.
I think he would meet Dracula first. Dracula is the owner of the hotel and is always on the lookout for new guests or any potential threats. When Harry Potter shows up, Dracula would be there to greet him, albeit a bit warily as he doesn't know what to expect from this wizard from another magical realm.
Well, he might be really confused at first. The magical world he knows from Hogwarts is quite different from the spooky yet fun world of Hotel Transylvania. Maybe he'd try to use his magic wand to do normal things like open doors, but the doors in the hotel work in their own strange ways. He could also meet all the unique monsters and have to learn their customs and cultures, which would be a whole new experience for him.
Another fanfiction could involve a spell gone wrong in the Harry Potter universe that transports some of the Hogwarts students to Hotel Transylvania. The students then have to adapt to this new and strange place, and they could teach the vampires and other creatures about magic from their world, while also learning about the unique abilities of the hotel's inhabitants. For example, the werewolves in Hotel Transylvania could compare their transformation experiences with those of the werewolves in the Harry Potter world.
It could be really interesting. Picture Drac from Hotel Transylvania sending his daughter Mavis to Hogwarts. The magical creatures in the Harry Potter world could interact with the spooky but friendly monsters from Hotel Transylvania. For example, Hagrid might befriend Frankenstein's monster. And the spells in Harry Potter could be used in the Hotel Transylvania setting, like using Lumos to light up the dark corridors of the hotel.
In some fanfics, like 'The Unlikely Alliance', a major plot twist is that Voldemort teams up with Dracula. It's unexpected because they come from different fictional worlds, but their shared desire for power makes them form an alliance. This changes the whole dynamic as Harry and his friends now have to face two powerful enemies at once.
There's also 'Potter in Transylvania'. It's a shorter but really engaging fanfic. In it, Harry is on a solo mission that leads him to the Hotel Transylvania. He has to use his magic skills in a completely new environment filled with vampires, werewolves, and other spooky creatures from the Hotel Transylvania world. The story focuses on how he adapts and uses his knowledge to get out of tricky situations.
Harry could meet some local magical creatures that are unique to Africa. For example, there could be a magical creature similar to a hippogriff but with different characteristics. And he may also meet African witches who are experts in herbal magic, which they use to heal and protect their communities. They could teach Harry some of their techniques and knowledge.
He could meet Fleur Delacour's family. Since Fleur is from France, her family might be an important part of the French wizarding community that Harry interacts with.
He might meet international aurors. These are highly skilled wizards from different countries who are experts in dark wizard catching. They could teach Harry some new combat spells.
He might meet Canadian witches and wizards. There could be a friendly wizard who shows him around the Canadian wizarding community.
The characters from Hotel Transylvania could be new students at Hogwarts. Dracula could be a teacher of some sort, perhaps teaching about dark creatures in a different way than Hagrid. His bat form could be mistaken for a dark omen by some students at first.