If Harry is Salazar, he might have enhanced Parseltongue abilities. Salazar was known for his connection with snakes, so Harry could communicate with a wider variety of serpents and perhaps even gain more control over them. For Draco as Godric, he could have a stronger affinity for Gryffindor - like magic, such as a more powerful Patronus, perhaps in the form of a lion, representing Godric's courage.
In this fanfiction, Harry as Salazar might be able to access ancient forms of magic related to the founding of Hogwarts. This could include the ability to unlock hidden chambers or secrets within the castle that were originally Salazar's domain. Draco as Godric could have a natural gift for sword - based magic, as Godric was famous for his sword. He might be able to summon a magical sword at will, or imbue his regular wand with the properties of a sword for more powerful spell - casting.
Well, in such a fanfiction, the relationship between Harry and Draco would likely be a complex reimagining. Since Harry is seen as Salazar and Draco as Godric, they might have a relationship based on the historical enmity and respect that Salazar and Godric had. They could be rivals, constantly testing each other's skills and knowledge, yet also having a grudging respect for one another due to their 'founder' status.
Perhaps Draco could be a Kneazle. Kneazles are intelligent and independent, which would suit Draco's personality. As a Kneazle, he might be constantly sneaking around and getting into places he's not supposed to. Harry would have to use his wits to keep Draco out of trouble and also earn his trust, as Kneazles can be quite picky about who they bond with.
He could use a truth - revealing spell like Veritaserum. This would force Draco to tell the truth, and Harry could judge him based on his honest answers. But using such a spell is unethical without proper authorization, which could also cause problems for Harry.
One adventure could be related to a mysterious magical artifact hidden somewhere in Hogwarts. They hear rumors about it and decide to search for it together. Along the way, they face challenges like magical traps set by previous Hogwarts students or even some dark magic that guards the artifact. But because they are twins, they have an unspoken understanding and are able to use their combined skills - Harry's bravery and Draco's cunning - to overcome these obstacles.
The son could be highly adaptable. Growing up with two such different fathers, he would be exposed to different ways of thinking. He might have Draco's slyness when it comes to getting out of tricky situations, but also Harry's selfless nature when it comes to helping others. He could also be very good at magic as he would inherit the strong magical genes from both his fathers. And he would probably be a bit of an outcast at Hogwarts, not fully fitting into either the Slytherin or Gryffindor mold.
He would most likely be very skilled in academic magic. Given Hermione's expertise in spells and Draco's family's long history of magic, he could be a prodigy in subjects like Transfiguration and Potions. Maybe he'd have a natural talent for non - verbal spells, like Hermione, and also be able to perform complex dark - arts - related spells with ease, but use them for good, unlike the traditional Malfoy use of such magic.
One magical element could be an enchantment that allows the fan to adjust its speed based on Harry's body temperature. So if Harry is really hot, the fan speeds up automatically. Another could be a charm that makes the fan blend in with the Hogwarts decor when not in use, like it turns into a small quill or something. Also, Draco might use a spell to make the fan levitate slightly, so it can follow Harry around and keep him cool wherever he goes in the room.
Well, it could inherit some of Harry's skills like Parseltongue perhaps, given its connection to Slytherin's heritage through Harry. And from Fleur, it might have an affinity for water magic since she has Veela heritage. Maybe the baby could also have strong defensive magic abilities as both Harry and Fleur have shown great courage and the ability to defend themselves in tough situations.
In the fanfiction, Draco's shop could have a special love potion. However, it's not the regular love potion but a more refined version that has a milder effect. Also, there could be a potion that helps with sleep, which is much needed for those who have trouble sleeping due to nightmares caused by dark magic.
In this fanfiction, Draco would flaunt his family's signature spells. His magic would be more calculated and strategic, like setting up magical traps before the duel even starts. Harry's magical abilities would be more about his connection to his friends and the positive energy that gives him. He could use magic that is enhanced by his loyalty and friendship, like a spell that gets stronger the more he thinks about protecting those he cares about. During the duel, both of them would have to constantly adapt their magical abilities to counter each other's moves.