Well, it's likely that there could be a wizard or witches who have turned to a life of crime for personal gain. They might be the ones who directly stole the money. However, there could also be a bigger, more menacing force behind them. Maybe a powerful dark sorcerer who is using the stolen money to fund his evil plans and will stop at nothing to keep Harry from getting it back. There could also be some magical creatures that have been corrupted by dark magic and are helping the thieves hold on to the money.
Well, in this fanfic, Harry might use his wits and magic skills to track down the thieves. He could face various challenges and obstacles along the way. Maybe he has to infiltrate a secret hideout or outwit a powerful dark wizard who has the money. He'll probably also have some allies to help him in this adventure.
It could be a disgruntled house - elf. Maybe one that was mistreated by its wizarding family and decided to steal money as revenge. They could use their magic to get into places unnoticed and take the money.
One possible antagonist could be Orochimaru. He has always been interested in Naruto for his Nine - Tails power, so it would make sense for him to be a threat that Kakashi has to protect Naruto from.
It could be some powerful demon lords in hell. They might see Naruto as an intruder and try to stop him from whatever his goal is.
There could be a group of rogue witches and wizards who are against the current system in the wizarding world. They oppose the Ministry of Magic's rules and see Harry Potter as a symbol of the establishment they want to overthrow, so they become the antagonists.
Obviously, Harry Potter is the main character as it's about him reclaiming the Potter heirlooms. There might also be Hermione and Ron, as they are Harry's closest friends and often accompany him in his adventures. And perhaps some members of the Potter family from the past could be mentioned or even appear in some magical way, like through memories or portraits.
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.
It could be some dark wizards who have somehow gotten hold of the nuke and plan to use it for their evil purposes. They might be in league with some Muggle villains who know about nuclear technology.
A group of jealous students could be the main antagonists. They might be envious of Harry's natural talent and the attention he gets from the teachers. So, they try to sabotage his progress at the gifted school by setting him up to get in trouble or stealing his study materials.
Maybe a group of anti - magic fanatics within SHIELD itself. They see Harry's magic as a threat and try to undermine him at every turn. They could be secretly working with external forces that also oppose the use of magic in the world of SHIELD. Harry would have to prove that his magic can be an asset rather than a liability.