Very engaging story! The book excerpt at the beginning really drew me in. I was anxious for Sam to get his memories back and to learn why he said yes, but I realise that wasn't the story you were telling! I came to grips with that when I read

Dean swells with joy and pride and anticipation (I'm gonna get my Sammy back, he's not lost, one day he'll remember everything I did for him, he'll remember, really remember that I'm his Dean)

which definitely had the ring of something that was never going to happen!

It's all so vivid, with so many memorable incidents like Dean breaking his leg and Sam discovering dental floss!