One possibility is that the baby could possess a unique form of Patronus magic. Harry's Patronus is a stag, and Fleur being a half - Veela could influence it in an interesting way. It could be a hybrid - like Patronus or have some special properties. Additionally, the baby might show an aptitude for potion - making, as both Harry has had to deal with potions in his Hogwarts years and Fleur's magical background might contribute to a natural understanding of ingredients and their combinations.
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.
One possible plot could be that the baby has unique magical abilities. Since Harry has his own set of powerful magic and Fleur is part Veela, their baby might inherit a combination. Maybe the baby can communicate with magical creatures in a special way, leading to adventures where they all have to protect the baby from those who might want to use its powers for evil.
The baby could have the power of compulsion like Klaus, being able to influence the minds of others. Since Elena was a vampire too, the baby might also inherit enhanced strength and speed.
There's a possibility that the baby could inherit Knuckles' connection to the Master Emerald. Maybe the baby would have some sort of enhanced intuition when it comes to protecting powerful artifacts. From Rouge, the baby could inherit her stealth skills. Rouge is very good at sneaking around, and this could be a useful ability for the baby to have, especially if they get into adventures in the fanfiction world.
The baby could have Naruto's ability to use the Rasengan. Since Naruto has mastered this powerful technique, it might be passed down genetically or through training. Also, it could inherit Samui's intelligence and strategic thinking. This combination would make the baby a very formidable ninja.
The baby might have the ability to communicate with magical creatures in an extraordinary way. Since Hermione is so good at studying and Draco has some pure - blood magic knowledge, their baby could inherit a special understanding of different species. For example, it could be able to calm a hippogriff just by looking at it, or have a natural bond with house - elves, understanding their needs and wishes without them having to speak.
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.
He could have the ability to control time, like his father the master. This would be a very powerful and unique ability. He might be able to freeze time during a battle or rewind time to correct a mistake.
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.
The baby could have the power of teleportation. Since both Dean and Castiel are involved in a world full of supernatural elements, teleportation would be a useful power. It could help the baby escape dangerous situations or quickly reach its parents when they are in trouble.
Well, they could have all sorts of adventures. Maybe the baby cousin has some sort of special magic that Harry doesn't know about yet. For example, the baby cousin could be able to communicate with magical creatures in a unique way. And Harry, being the curious and brave wizard he is, would want to explore this new aspect of magic with his little cousin. They might go on a journey to find a rare magical creature that only the baby cousin can sense.