There was a time when he had had Dean Winchester quivering in front of him like a naughty school child. There was a time when Dean Winchester had talked of him in hushed tones, been reduced to breathlessness every time he appeared. But then he had fallen. Now it was he that was a child. A baby in a trench-coat.
One might say that he deserved it. He had kept secrets from Dean, betrayed his trust, sins that Dean Winchester found hard to forgive, even in his own brother. He wondered why he and Sam were not better friends; they had so much in common. But it was not the secrets that had first alienated Dean, it was the revelations. He had exposed himself too much to Dean, been too forthright about the human's importance to him, and from that time Dean had begun to withdraw, begun to mock him.
Now no amount of miracles he performed could pierce the barriers that Dean had erected. Dean would use him but not admit him. He was less than a child now. He was no more than a dog to perform tricks, rollover, sit up and beg.
Perhaps it was inevitable. If you follow someone around like a dog, eventually they will tell you to go fetch.