Maybe Minato would first gather all his remaining chakra and create some sort of a spiritual connection with Naruto. He might then show Naruto visions of their past together, the love he has for him as a father, and how they could be together again. This could be a way to draw Naruto towards him. Another option could be that Minato tries to find a way to reverse whatever it was that separated them in the first place, perhaps by seeking out some ancient and powerful artifacts or knowledge.
Well, in some fanfictions, Minato might use his powerful jutsu to break through the barriers between the living and the dead and directly reach Naruto. He could also try to influence the people around Naruto to bring him closer to where Minato is, like using his spirit to communicate with Naruto's friends and convince them to help.
In certain fanfiction scenarios, Minato could enlist the help of other powerful ninja. For example, he might convince the Sage of Six Paths to assist him in getting Naruto back. He could also try to manipulate the fabric of time and space, if he has the power or knowledge to do so in the fanfiction world. Since Minato was a very intelligent and powerful ninja, he would likely explore all possible means to be reunited with Naruto. He might even try to bargain with some dark forces, if it means getting his son back, but this would come with its own risks and consequences.
One reason could be that Minato has some unfinished business with Naruto. Maybe he wants to pass on some crucial ninja skills or knowledge that only he can teach. Another reason might be the strong father - son bond. Despite being separated for so long, Minato's love for Naruto is still very deep.
Maybe they enlist the help of other powerful ninjas. For instance, they could ask Tsunade for medical support in case Naruto is injured. They could also get intel from Shikamaru, who is known for his intelligence. By gathering a team of reliable and strong ninjas, they increase their chances of getting Naruto back successfully.
She might start by using her knowledge of Naruto's past. Since she is his mother, she knows things about his early life that no one else does. She could use these memories to create an emotional connection with him. Maybe she'll show up in his dreams first, like a hazy memory, and then gradually reveal herself in the real world.
Kushina could also seek the help of other powerful shinobi. For instance, she might ask Minato for assistance. Since Minato was Naruto's father and also a very skilled ninja, together they could come up with a plan to reunite with Naruto. Maybe they would use some sort of space - time ninjutsu to get closer to him.
In some fanfictions, Minato saves Naruto physically. For example, he might use his teleportation jutsu to appear right in the middle of a fight and whisk Naruto away from danger. In others, he could save Naruto spiritually. He might enter Naruto's mind, like in the fanfic 'Minato's Mind - Saving Mission', and give him the strength and confidence to overcome his inner demons. Sometimes, Minato saves Naruto from a political situation. For instance, in 'Minato and the Hidden Leaf's Politics', he uses his influence and wisdom to protect Naruto from being used as a political pawn.
He uses his skills as a ninja to protect Naruto. He sets up special seals around Naruto's crib to keep out any potential threats. Also, Minato might try to use his chakra to boost Naruto's weak body. He would transfer his own life force a little bit at a time to help Naruto fight the sickness, which is a huge sign of his love.
Minato's presence can have a huge impact. He can act as a mentor, teaching Naruto things he never knew about his family and heritage. His wisdom and skills can inspire Naruto to reach new heights in his training and ninja development.
Minato might show his protectiveness by always being near Naruto in spirit. For example, he could leave behind some kind of jutsu or power that activates when Naruto is in great danger, like a hidden seal that releases a powerful defense.
He could feel it through a shared chakra link. Since they are related and Minato sealed the Nine - Tails in Naruto, there might be a latent connection that gets activated in the fanfiction, allowing him to sense Naruto's pain on a physical and emotional level.
Naruto could incorporate Minato's sword - fighting skills if he has any in the fanfiction. Minato was known to be proficient with weapons. Also, Naruto might use Minato's strategy of quickly assessing the enemy's weaknesses and then striking precisely at those points. He could even use some of Minato's signature jutsu in a more efficient way, like the Rasengan, but with Minato's finesse.