Itachi and Sasuke.

From a young age, Itachi was calm and insightful, showing maturity for his age and knowledge of how to handle any situation. For all his accomplishments, talent, and fame, Itachi was a rather humble man. He never boasted about his abilities or underestimated others, and most of what he said was dispassionate and to the point. If an opponent exceeded his expectations or posed a legitimate challenge to him or his allies, Itachi freely acknowledged it.
When Sasuke was young, he was very kind, loving his parents and Itachi, respecting his clan members, and his teacher.[10] He was proud to be Itachi's brother and Fugaku's son, who were both loyal protectors of Konoha, and Sasuke wanted to be like them. His original dream was to serve in the Konoha Military Police Force when he grew up, in hopes of gaining his father's approval and recognition of his abilities.

Sasuke was very young and energetic, and Itachi was like an older brother to Sasuke, outgoing but a little withdrawn.