Proto Man is calm, cool, collected in any situation. He is also shown to be greatly independent.
As someone who values his individuality so much, he risked body failure just to avoid becoming someone else. He also despises others who were either made in his image or were based off him in some way.
He plays an older brother role with Mega Man by helping him out and giving advice, and even saves his life on a few occasions. He is a loner who, similar to his brother, has a strong sense of justice and helps those who need it. He is also a grateful person as shown by how he repays Wily's debt for temporarily fixing him.