You know, we all talk about how happy Dean will be if he and Cas get together, and how happy Cas makes him. But i like to use a different word for it. Peaceful. Cas does bring Dean a lot of happiness, yes, but Dean's been happy before with others. It's a hollow emotion, inadequate without peace, and Dean has definitely never had that. He's so restless, in all aspects of himself and his life. But Cas brings him peace. It's like Cas's very presence just says "Be still."
*quietly sings Carry On Wayward Son and cries for a while*