“I waited for you”
Rory began as “the nurse,” a character in the background of the show. He wasn’t special, or clever, he was just Amy’s tentative fiancée.
Even Amy wasn’t sure about him. She abandoned her wedding, and tried to jump the Doctor. He was so frightened by the fact that the little girl who got him an apple was now a gorgeous and horny woman that he ran to get Rory to be a buffer.
And that’s all Rory really was for a while: a buffer. Rory like the Doctor and all, but he really wanted to get back to a real life with Amy, an old cottage and a couple of kids. Then he died, and was erased from time and space. And that is when Amy realized she really loved him. She was quietly sad for the next few episodes, and when Rory returned their reunion was beautiful.
But Rory, like Mickey, was never very secure with his position in Amy’s heart. He could never quite believe that she loved him as he loved her, even saying exactly that in the premiere of the Seventh Series. He was never sure Amy loved him more than the Doctor.
Rory was like Mickey in that he was an afterthought. He and the Doctor would never have solo adventures, and he would never single handedly save the world. Without Amy, Rory wouldn’t exist.
And Rory was all right with this, because he adored Amy. She was the only thing he cared about, and he was ready to sacrifice anything for her. It slowly became clear that Amy too loved Rory, although in her case the love clearly grew. But because Rory would do anything to be with Amy, would give up anything and risk the universe itself, he didn’t mind that he couldn’t write his own story.
Rory was never a great hero. There were no epics written of him, and no legends about him, no matter what Amy tried to tell her daughter. He loved with his whole being, and it consumed everything else about him. And he was just fine with being called Mr. Pond.
But even at the close, Rory was never as important as Amy. He vanished without even a last farewell, a last moment to himself. He died as he lived, caught up in the lives of those around him, unable to control anything himself. But he died with Amy, knowing that Amy loved him as much as he loved her. And so, he probably never really minded being a +1.