So, after hearing the song, and watching the video, I finally get the true meaning of the song...
It's about relying on someone to be on your side, even when you change for the worse. The song tells a story on how far a friendship can go, even when one does something very bad, and they still expect the other to come with, but it all ends in a somewhat "betrayal". That's what happened when Catnap entrusted her life on the Prototype, and was expecting DogDay to follow along. To be honest I don't know if it was the cat's or dog's fault the whole thing happened, but no matter what it's such a great song... if you haven't heard of it yet... PLEASE LISTEN TO IT!