In these fanfictions, a really cool plot twist could be that Moody, because of his experience with the dark arts, has knowledge of a secret power within Harry that even Voldemort doesn't know about. He nurtures this power in Harry, which makes Harry a completely different kind of threat to the dark forces. Maybe it's a power related to the ancient magic of the founders of Hogwarts that was passed down in a way no one expected.
Perhaps Moody, being a very experienced Auror, trains Harry in some dark magic defense techniques that are not taught at Hogwarts. This gives Harry an edge in fighting the dark forces but also makes the Hogwarts faculty a bit wary of him. He could then be in a situation where he has to prove that his knowledge is for good and not for dark purposes.
One interesting plot twist could be that Kami's magic is so different from the wizarding world's that Harry develops entirely new spells. For example, he might be able to use nature - based magic in ways wizards never thought of. Another could be that Kami's values of honor and purity influence Harry to take a different stance on the fight against Voldemort, perhaps trying to redeem him first. Also, the magical creatures in Kami's world could interact with the ones in Harry's world in unexpected ways, like a friendly competition between a hippogriff and a kirin.
In this fanfic, a really cool plot point might be how Moody's artificial eye plays a part in Harry's upbringing. Moody could use it to teach Harry about seeing through disguises and hidden threats. Also, Moody's no - nonsense attitude might make Harry a more disciplined wizard. He might not tolerate any sloppiness in Harry's magic, which would lead to Harry being a more precise and powerful wizard in the long run.
One interesting plot twist could be that Remus, being a werewolf, has to constantly protect Harry from those who fear his lycanthropy. This could lead to them having to constantly move, creating a nomadic lifestyle for Harry. Another could be that Remus teaches Harry different magic that is more in line with his own values, which might put Harry at odds with the traditional Hogwarts curriculum.
Well, a really cool plot twist could be that the Malfoys, who are raising Harry, actually start to change because of him. They become less prejudiced against non - pure - blood wizards. And Harry, in turn, uses his influence within the Malfoy family to bring about positive change in the wizarding world. It would be a complete turnaround from the original relationship between Harry and the Malfoys in the original series.
Maybe Harry would have a different view on the wizarding world. Growing up with the Delacours, he'd be exposed to a more international magical community from a young age. So, instead of being so focused on the British wizarding world's problems like Voldemort, he might be more interested in international magical relations and how to unite different magical cultures.
Perhaps a plot twist could be that the magical creatures interact with Harry differently. In the original, they had a certain way of relating to him, but in this fanfiction, being raised as a black wizard might make some creatures more or less friendly towards him. Some might see him as a symbol of change in the wizarding world and be more drawn to him, while others might be suspicious. Also, the way Harry approaches magic could be different. He might draw on cultural magic that is unique to his black heritage, which could give him an edge in certain situations or make him a target for those who fear change.
Perhaps the assassin is a double agent, and Moody's betrayal is part of a much larger scheme. The assassin could be pretending to be betrayed to gain the trust of the real villains. So, the assassin then uses this new - found trust to gather information and save the day in the end. Another plot twist could be that Moody is not the real Moody, but an impostor who betrays the assassin for reasons related to the impostor's true identity and motives.
One possible plot twist could be that Kenpachi's rough and battle - hungry nature makes Harry a much more aggressive wizard. Instead of waiting for Voldemort to come to him, Harry might actively seek out dark wizards to fight. Another twist could be in the way magic is taught. Kenpachi, not being from the wizarding world, might introduce Harry to a more physical and unorthodox way of using magic, like using brute force in spellcasting rather than the traditional finesse. Maybe Harry would also develop a more carefree attitude towards the rules of the wizarding world, much like Kenpachi does with the Soul Society's rules.
One interesting Moody fanfiction could be where he mentors Harry in a more in - depth way outside of the classroom. It might explore Moody's past experiences with dark wizards and how he imparts that knowledge to Harry for future battles.