And no, it’s not “Because Arthur Darvill.” Don’t get me wrong, I love me some Arthur Darvill, and he plays the part like a maestro, hitting all the right notes, but Rory’s genius is in the writing.

When we first meet him, he’s completely overshadowed by the amazing that is Amy Pond. We know Amy. We love Amy. She gave The Doctor fish fingers and custard. And sure, she’s dating this guy, this nurse, but that’s only because she’s stuck in that small village waiting for The Doctor, we think.

But the next thing we know, Amy’s about to marry the nurse. No worries, though. She’s run off with The Doctor and it could be a few seasons before she makes it back to her wedding. After all, Donna never did get married.

And then Rory joins the cast. He gamely plays Amy’s brother in Venice. He fights. He runs. He stands by Amy no matter what. And when anyone is really in trouble, who do you want? A doctor? No. Doctors just give orders. Nurses actually take care of people. When things really get bad, Rory jumps in and heals people with actual medical know-how.

And then he’s gone. Vanished from history. And when he comes back, he’s the Last Centurion. And once he and Amy are married, Rory loses all his insecurity. He attains a quiet assurance that nothing can really go wrong in the world, because Amy is okay, and as long as Amy is okay, everything is okay.

Once we find out their whole story, it almost seems like Rory is a doormat, until you really think about it. Sure, Rory pined for Amy through his teen years, too shy to say anything. But it’s not like Amy was out dating anyone else. Amy wasn’t his girlfriend, but she was with him, and that was good enough. In every reality, Rory is ready to do anything for Amy, but that’s what’s so great about him. His love for her is so strong that it gives him strength to sit for two thousand years, or to withstand the pain of an eye drive, or to give her the divorce he thinks she wants. And in every reality, Amy has to realize that she needs to deserve that. It’s not easy to receive that kind of love.

Because in the end, Amy gives up the Doctor for Rory. And we have to understand that she made the right decision. We have to see the pain that decision causes the Doctor and we have to keep loving Amy for knowing who loves her most in this or any other universe. Otherwise, the Doctor’s pain would be hollow, and we would resent him for spending time with Clara. And worse, River Song would have given up her regenerations for someone who loved a selfish friend. But Amy is not selfish, she just understands that she loves Rory every bit as much as he loves her, and she can’t live knowing that she had a chance to be with him and didn’t take it.

Best character ever written.

Update: *Yes, I know he thinks he’s a Williams. He’s a Pond.