Another possible antagonist could be a dark wizard who has a special interest in the wands that Harry is stealing. This dark wizard might want these wands for his own evil plans and sees Harry as a competitor. So, he would try to stop Harry from stealing the wands while also trying to get his hands on them himself.
Maybe Harry steals wands to gain more power in the wizarding world. He could be on a secret mission to collect powerful wands that are hidden away. By stealing these wands, he might be trying to tip the balance of power in his favor against some dark forces.
There could also be some within the wizarding community who oppose Harry learning the Unforgivables. They might see it as a sign that he is turning to the dark side and try to stop him, so they could act as antagonists in the story.
Ron and Hermione are the most likely ones. They are his best friends and have always been by his side through thick and thin. They would probably follow him without hesitation and use their own skills, like Hermione's vast knowledge and Ron's loyalty and practical skills, to assist in the ship - stealing adventure.
Some of Harry's friends could also be antagonists in this fanfiction. They might not understand his reasons for wanting to destroy the wizarding world and try to stop him. For example, Hermione, with her love for knowledge and the wizarding world's institutions like Hogwarts, would probably try to reason with Harry and, if that fails, might even fight against him to protect the world she loves.
Voldemort and his Death Eaters would be obvious antagonists. They could be constantly hunting for Harry and Tonks as they are seen as threats to Voldemort's plans for total domination of the wizarding world.
Some pure - blood supremacist wizards could be antagonists. They don't like the idea of Harry creating a haven for all kinds of wizards on the island. They might try to sabotage the island's creation or attack it once it's made, fearing that it will disrupt the 'purity' of the wizarding bloodlines.
The remaining Death Eaters could be the antagonists. Even though Voldemort is gone, there could be some who still hold a grudge against Harry and want to finish what their master started. They might track Harry and Ginny down as they run away, creating dangerous situations for the couple.
Maybe some jealous students from Hogwarts or Beauxbatons. They don't like the idea of Harry and Fleur being together and running away to have an adventure. So they try to sabotage their plans, perhaps by spreading false rumors or even using minor hexes to slow them down on their journey.
There could be other vampire clans that see the Cullens' camping trip with Bella as a threat or an opportunity. They might try to disrupt their time in the woods. Another possibility is that some shape - shifters in the area don't like the presence of vampires and decide to cause trouble.
The villagers themselves could be the main antagonists. Since Naruto has given in to hate, he may see the villagers' past mistreatment of him as unforgivable. Their judgmental and often cruel behavior towards him in his childhood could now be the reason he turns against them, making them the antagonists in this new narrative.