Maybe through some kind of magical encounter. For instance, he could stumble upon a portal that leads to a world where the Keyblade exists and be chosen by it. It could be that his strong will and desire to protect his friends are what draw the Keyblade to him.
Well, he'd probably be an even more powerful force. The Keyblade has its own unique powers and abilities. Naruto's already strong ninja skills combined with the Keyblade could make him nearly unbeatable. He might use it in combat in ways similar to how he uses his ninja tools, but with added magical elements. For example, he could use his chakra to enhance the Keyblade's attacks.
One possible plot could be that Naruto, who somehow gets access to a Keyblade, teams up with Aqua. They might go on a journey through different worlds, combining Naruto's ninja skills and Aqua's magic. Maybe they are on a quest to save both their home worlds from a common threat.
In 'naruto keyblade bloodline fanfiction', a really cool concept could be the idea of different Keyblade forms being related to the ninja clans in Naruto. For instance, the Uchiha clan might be associated with a Keyblade that has fire - based powers, similar to their use of Fire Release jutsu. This would create a whole new dynamic in battles and character development within the fanfiction.
It might also be possible for new characters to be the main characters in this fanfiction. For example, a young ninja who discovers a Keyblade and has to learn how to use it while also dealing with the politics and power struggles in the Naruto universe. They could be from a minor clan but rise to prominence through their Keyblade skills.
One possible storyline could be that Goku is accidentally transported to Alucard's world. They start off as enemies but then gradually learn about each other's powers and come to respect one another. Another could be that a powerful villain manipulates them into fighting each other. In this case, they might realize they are being used and team up against the real enemy.
It's really hard to say. Goku is extremely powerful with his Super Saiyan forms and incredible combat skills. But Alucard has his vampiric powers like immortality and the ability to control shadows. In a fanfic, it could go either way depending on how the author wants to write it. Maybe if the author wants to emphasize speed, Goku might have an edge. But if it's about dark, mysterious powers, Alucard could come out on top.
In a Goku Naruto crossover, both characters have their own strengths. Goku's physical strength and energy attacks are off the charts. His ability to instantly teleport and sense ki gives him an advantage in combat. Naruto, though, has a unique power system. His connection to the Nine - Tails and his ability to use different types of chakra make him a force to be reckoned with. If we consider a battle, Goku's power might seem greater on the surface. But Naruto has the advantage of being able to surprise his opponents with his ninjutsu and clones. Also, Naruto has a strong willpower that has allowed him to overcome many tough situations, which could play a role in a fight against Goku.
Naruto's chakra - based powers like Rasengan could be combined with Aqua's water - based magic through the Keyblade. Maybe the Keyblade can absorb Naruto's chakra and transform it into a new form of attack when used in conjunction with Aqua's spells.