[It's the part about vengeance being lonely that gets to Jason. After coming back from the dead and learning Bruce didn't avenge him, Jason knew his journey to becoming the Red Hood was going to be a lonely one. He knew most people weren't going to agree with him. He chose to be alone, didn't he?

He's still not looking at Bruce as he balls his hands into fists.]

I'm not doing this just for myself, you know.