When Blue first appears he is standoffish and keeps his heart closely guarded letting only his grandfather and his Pokémon into it. He treats his Pokémon like family and would hate to see them hurt because of his weakness. Blue will do any and everything in his power to keep his heart, and those in it, safe. Blue's relationship leads him to take Pokémon training very seriously. He believes that a trainer’s duty to his/her Pokémon is to help them improve but, also, acknowledge their limits.
“Always know your limitations. If you don’t then you’re only beating up yourself.” (Page 16, Chapter 01)
Blue is also strong and independent. He often refuses the help of others and finds other people to be unreliable. Blue is willing to face several powerful Pokémon trainers and members of Team Rocket alone if it means he doesn't have to rely on Red or any other trainer. Blue has no qualms about being on his own and when given the chance trains Blue takes the opportunity to himself and his Pokemon in complete solitude with almost no connection to society.
As the series progresses Blue learns to accept others into his heart and expand his circle to include both his family and friends. Blue also learns importance of treating all Pokémon with respect and taking care of them. Blue begins to see the lives of Pokémon outside of his own, something Blue never thought to consider before he met Red.