Who could be the most likely character to be a 'Harry Potter Trained Killer' in fanfiction?

In the 'Harry Potter Trained Killer' fanfiction, the plot could revolve around a time - traveling scenario. Harry Potter, having seen the future destruction of the wizarding world, decides to train a person from the past to be a killer. This person then has to go through a series of adventures and challenges. They have to learn combat skills from Harry, as well as how to be stealthy. Along the way, they discover secrets about the wizarding world that even Harry didn't know, and they have to use their new - found killer skills to protect these secrets from falling into the wrong hands.

Obviously, Harry Potter and Godric Gryffindor. There might also be some other Hogwarts founders making cameo appearances.

Obviously, Harry Potter would be one of the main characters. And then, there would probably be some members of the SAS. They could be tough, experienced soldiers who take on the task of training Harry.

Obviously, Harry Potter and Flitwick are the main ones. Harry as the student being trained and Flitwick as the trainer.

I think Harry and Blake could also be paired well. Blake's intelligence and her past experiences with the White Fang could be complemented by Harry's knowledge of fighting dark forces. They could bond over their shared experiences of fighting against those who want to bring harm and chaos, whether it's the Grimm in Remnant or Voldemort in the wizarding world.

She could be an ancient Celtic goddess, like Brigid. Brigid is associated with magic, healing, and smithcraft in Celtic mythology. In the fanfiction, she might see Harry's potential and decide to train him in her unique magical arts.

There's a chance it could be a powerful house - elf. House - elves are known for their own brand of magic, and one particularly rebellious or enlightened house - elf could decide to train Harry in magic that is more about stealth and quick - thinking. After all, house - elves have to be very sneaky to avoid detection by their masters most of the time, and this kind of skill could be very useful for Harry in his battles against Voldemort.

Maybe it's a former Death Eater who has seen the error of his ways. He wants to atone for his past sins by training Harry to defeat Voldemort. He has inside knowledge of the dark side's tactics and uses this to make Harry a more formidable opponent.

It could be a deranged fan who has found a way to bring their dark fanfiction ideas to life. This person might be jealous of the original story and wants to create chaos in the wizarding world through their fictional concepts made real.

A new, unknown villain. Maybe a brilliant scientist who turns to the dark side after a personal tragedy. This villain could create a weapon specifically designed to counter Batman's abilities, like a suit that can absorb all of Batman's punches and then redirect the force back at him, ultimately killing him.