Drawings of Characters Back-to-Back - Undeniable Trust

When two characters are back-to-back, their faith in each other is very clear. Are they defending each other in an epic battle or are they just casually leaning against one another? Regardless, their trust is almost palpable.

Hawkeye and Mustang from Fullmetal Alchemist are an iconic duo for their unwavering faith in each other, but what do you think of the other characters featured?