Well, Naruto could develop a more brooding side similar to Gaara. Gaara carried a lot of pain and loneliness inside. If Naruto becomes like him, he may start to show less of his sunny disposition and instead seem more burdened. He might be more distrustful of others as Gaara was in the beginning, always on guard and not as open to making new friends or alliances.
Naruto might become more withdrawn like Gaara was initially. Gaara was isolated due to his power and the fear others had of him. So Naruto could start to keep to himself more, losing some of his boisterous and friendly nature.