"I think Loki is so defined by Thor and in opposition to him, Thor is defined by Loki. They are these two brothers who love each other and hate each other, and need each other. They are Yin and Yang in a way.
The interactions between Thor and the other Avengers. Always puts a smile on my face. The next Avengers movie should definitely have a funny scene with this in it. XD I feel like Thor would call him metal man though.
This image precisely outlines the hero versus the villain. This binary then also shows that without the villain, there cannot be a hero and vice versa. The word "And" implies that along with Thor's caption, Loki is responsive to Thor's existence.