In some fanfictions, they might develop a more equal partnership. Naruto has grown a lot and in the ANBU, they are both elite ninjas. They could rely on each other's strengths. Naruto with his raw power and Kakashi with his intelligence and experience. They would share their thoughts and feelings more openly, and their bond would become stronger as they face dangerous missions together. For example, during a mission where they are outnumbered, Naruto might come up with a bold plan based on his intuition, and Kakashi would support him wholeheartedly because he trusts Naruto's abilities.
They could develop a mentor - apprentice relationship. Kakashi already has some experience mentoring Naruto, and in the ANBU setting, he could teach Naruto more advanced and stealthy techniques. Naruto would look up to Kakashi even more and try to learn as much as he can.