Dean Winchester had a heart of gold. He grew up having to care for Sammy, which he did gladly. It molded him into a selfless man, willing to put everyone ahead of himself. That pure heart let him save people by putting himself in danger.
Dean protected his family fiercely with that heart of gold. He never touched them, even when they were possessed and beating the shit out of him. He even sold his soul and went to hell for Sammy.
Dean Winchester had a heart of gold, but the demon inside turned it into a heart of stone.
I got inspired after the sneak peek of season 10 *flails*. Review please!