It could be part of an ancient magic experiment gone wrong. In the past, some wizards were trying to bring extinct creatures back to life for various reasons. The Spinosaurus was one of the results, and it has been living secretly in the wizarding world ever since. In the fanfiction, it could be that Hermione discovers some old scrolls about this experiment and they start to search for the Spinosaurus.
The Spinosaurus might be a guardian of a hidden magical power source. The legend says that only those who can befriend the Spinosaurus can access this power. Harry and his friends, always in search of ways to defeat Voldemort, hear about this legend and set out on a journey to find the Spinosaurus and gain the power it guards.
A Spinosaurus could be magically created by a dark wizard as a weapon. But then it breaks free and wanders into the Forbidden Forest. Harry and his friends would then have to find a way to either tame it or get rid of it without harming it too much.
There could be a fanfiction where a wizard or witch has the ability to communicate with the Spinosaurus and they form an unlikely alliance. This alliance might be crucial in a battle against the Dark Lord, with the Spinosaurus's strength being a great asset. For example, the Spinosaurus could help defend Hogwarts by using its powerful jaws and large size to fend off the Death Eaters.
Harry Hook often fits in as an alternate version or a new character added to the existing Harry Potter universe in fanfiction. He can bring new storylines and interactions.
Riku might be a character who has been summoned to the 'Harry Potter' world by a powerful spell gone wrong. Once there, he has to adapt to the rules of magic in this new world. He could start by learning basic spells at Hogwarts and gradually become a key figure in the fight against the dark forces, using his own brand of courage and determination that is different from the typical Hogwarts students.
The Bard can fit as a new kind of magical being. He could bring his own brand of magic, perhaps music - based magic, that is different from what the wizards in Hogwarts are used to. For instance, he might be able to use melodies to heal wounds or break curses.
It could be that Element 115 is related to the dark arts in the fanfiction. Maybe it was once used by dark wizards to create powerful and evil spells, and now it has resurfaced, causing a stir in the wizarding world. It might be up to Harry and his friends to figure out how to deal with it. This would add a new and exciting plotline to the familiar 'Harry Potter' world.
Well, in fanfiction, the 'Harry Potter Lantern' could be a part of a new sub - culture within Hogwarts. Maybe there's a group of students who study the Lantern's magic and they have their own secrets and rituals. This could create a whole new set of relationships and rivalries among the characters. For example, the Gryffindors might want to use the Lantern's power for good, while some Slytherins might be tempted to use it for more self - serving reasons.
The Infinity Stones could also change the magic system. In the Harry Potter universe, magic has certain rules and limitations. But with the introduction of the Infinity Stones, those rules could be bent or broken. For example, a character could use an Infinity Stone to perform magic without a wand, or to teleport across great distances without using apparition. This would create a whole new set of challenges and opportunities for the characters in the fanfiction.
Sasuke could be a foreign exchange student of sorts. His Sharingan might be seen as a very rare and powerful magical ability. He would likely be very good at Defense Against the Dark Arts due to his combat skills.
The Hulk could fit in as a powerful protector. His super strength can be a great asset against dark wizards. For example, when the Death Eaters attack, the Hulk could easily overpower them.
A nekomata could fit in as a rare and powerful familiar. It could be from a far - off magical land and brought to Hogwarts by accident or on purpose. For example, it might have been smuggled in by a dark wizard initially but then escapes and finds Harry.