Naruto might become more guarded at first. After being neglected, he may not be so quick to trust people in Kumo. But as he experiences the comradeship there, his more open and friendly side could gradually come back, just in a more mature way. He could also develop a different sense of loyalty, not just to his old village that neglected him, but to Kumo which gives him a new chance.
Well, one possibility is that Naruto could quickly rise through the ranks in Kumo. Since he was neglected at home, he might be more determined to prove himself there. He could form strong bonds with new friends and comrades in Kumo who actually value him, which would be a huge change from his situation in his original village.
His character might become more adaptable. Naruto is used to Konoha, but in Kumo, he has to deal with new rules and a different social structure. This could make him more flexible in his thinking. For example, he might learn to approach problems in a more Kumo - like way.
Naruto might become more cautious. After being kidnapped, he realizes the world is more dangerous than he thought. He could start to be less impulsive and think more before acting.
Well, it could be that Naruto, feeling neglected in his own village, decides to seek a new start in Kumo. Maybe he meets some unique characters there who accept him for who he is and he begins to train in their style of jutsu, thus becoming a stronger shinobi in a new environment.
Naruto's character might become more self - reliant. With no family support, he has to depend on his own wits and skills. So he becomes better at making quick decisions and solving problems on his own.
Naruto's character develops with a sense of resilience. Being neglected by his family, he becomes more self - reliant. He learns to fend for himself in the harsh Anbu environment.
Naruto's character would likely become more reserved at first. The neglect he has faced has made him a bit jaded. But as he proves himself in ANBU, his confidence would start to return. He would also become more stealthy and calculating, traits he didn't really have to rely on before. His sense of loyalty to the village would be tested and strengthened as he faces more complex and dangerous situations within ANBU.
His character could become more adaptable. In Kumo, he'd be exposed to different values and ways of life. This would make him more open - minded. For instance, he might start to view the concept of power in a new light, as Kumo has a different emphasis on strength compared to Konoha.
Besides Naruto, Yugito Nii could be a main character. She is a jinchuriki in Kumo, just like Naruto is in Konoha. They could bond over their shared experiences of being hosts. And there could be some of the Kumo elders who play important roles. They might be the ones who oppose Naruto's entry at first, fearing he could bring trouble, but then as they see how he can contribute to the village, their opinions change.
The Kumo ninja would likely be angry at first. They'd feel that Naruto, as a symbol of hope in the shinobi world, should have noticed their problems. But some of them might also be hopeful that Naruto's arrival would finally change things for the better. As for Naruto himself, he'd probably be shocked to realize how much he'd overlooked Kumo and would feel a sense of guilt.