Kurama might become angry at first. He's a powerful being and being neglected would likely wound his pride. He could start causing some minor disruptions inside Naruto, like making it harder for Naruto to access his chakra.
Well, Kurama might train Naruto by teaching him how to better control and access chakra. Since Kurama has a vast amount of chakra, it could show Naruto unique ways to harness and use it. For example, it could guide Naruto in creating more powerful and complex jutsu by using their combined chakra in a more efficient way.
Kurama makes a comeback in the manga. The return is well-plotted and adds an interesting twist to the story. It also ties up some loose ends and brings new possibilities.
Naruto's self - confidence gets a huge boost. Kurama's teachings are like a seal of approval. If Kurama believes in him enough to teach him, then Naruto must be something special. This new - found confidence shows in his posture, his speech, and how he faces challenges. He no longer doubts himself as much when it comes to difficult tasks, whether it's a tough battle or a diplomatic negotiation within the ninja world.
It could develop as Naruto spends more time in the mental space where Kurama resides. They start to communicate better, understand each other's motives, and gradually form a deeper connection. This might involve Naruto learning about Kurama's pain and loneliness over the years, which makes Kurama more open to Naruto. As a result, their bond becomes stronger and more symbiotic, allowing them to share power more effectively and support each other in different situations.