Kakashi Hatake

Kakashi was a strict, by the book person that never questioned the rules. Because of his strict following of the rules, Kakashi came off as a cold, heartless person. The reason for this is because when he was little (6 or 7), his father committed suicide because of his guilt and the harsh treatment he received from the village and his teammates after he abandoned a crucial mission in order to save his teammates' lives. Kakashi didn't want to end up like his father, Sakumo, so he started following the rules.

After the events of Kakashi Gaiden, Kakashi would adopt a lot of Obito's traits, like being late and the bad excuses. The real reason for his lateness is because he would visit the memorial stone in honor of all those he lost and to remind himself of his past mistakes.

Rin

Rin was a caring and friendly person and didn't look down on anyone. She was a smart, talented Medic Ninja that had saved the lives of her teammates many times. During the mission into Grass country to destroy a bridge, Rin got taken hostage. Rin showed her strong willpower by not giving in even when the Iwa ninja tortured her.

At the moment no one knows what happened to her, I believe that she was killed since Kakashi said that everyone he ever loved was dead.

Minato Namikaze

Minato was a fair teacher, never playing favorites. He never treated Kakashi, Rin, or Obito differently and he always corrected them, like when it came to their teamwork. He was a genius shinobi that held his teammates high above himself.

Minato would later become the Yondaime Hokage and die in his battle with the Kyuubi by sealing part of the fox inside his own son, Naruto.