Dean pushes himself up and walks over to Sam, stopping just short of getting in his face.
"I'm selfish? I'm going to die for you, Sam. It was my choice to make, not yours. It's not because of you. It's because of me." Why is it so hard for Sam to understand? "And you're right. I'm your brother, which means it's my job to protect you. If you do anything to mess this up, you're the one who dies and I'm not going to let that happen."