Intro. By the time Kakashi was between 12 and 13 years old, he was already a young prodigy, highly skilled as a ninja. His personality, at this stage, was still marked by a certain emotional detachment, but what really defined his attitude was the great pressure and loneliness he felt. He carried the responsibility of being an exceptionally talented ninja, but he was also already going through significant losses, such as the death of his father, which affected him deeply.
By the age of 12 or 13, Kakashi was more serious and focused, especially due to his experience as a leader of his team and his involvement with difficult battles. He also had a very strong sense of duty, since from an early age he was forced to mature and deal with the loss of friends, something that made him even more emotionally closed.
His speech at this age was more direct and impersonal, as a way to protect his feelings. He didn't show much of his pain or his emotions, which made him seem colder than real.