The Cab - Angel with a Shotgun Lyrics Meaning

I think it is about Sam and deans relationship and how Castiel gave up everything he had ever known to save one person, even when people claimed that Sam and Dean were insignificant humans, Castiel always and only talked about how important they are and the world can’t live without them. And he was right because he didn’t compare himself to them like the other angels did, he looked at everything they have done, and knew that it had made a difference, because if it weren’t for them, the apocalypse would have started and the world would be thrown into chaos and death. He looked at how much they could do, how amazing they are, and betrayed everyone he knows and changed completely, giving his life for them several times. His love for Sam and Dean even penetrated the empty when he died. The thing in the empty said that none had ever woken up, because they didn’t have someone they loved as much as Castiel loves Dean.