From the perspective as we learned about the sacrifices being made in the battle between Heaven and Hell, particular from the point of Castiel (Mischa Collins), who leaves his host body, Jimmy, in “The Rapture” and gets forced back to Heaven.

Jimmy awakens a year after being possessed by Castiel and has one thing on his mind. Seek out his family he left behind after agreeing to become a host vessel for an angel (which we see happen over the course of a number of flashbacks during the episode).  And it was a bittersweet reunion with his family tentative of him after a year away but the moments with his daughter and wife were touching and sad given he really didn’t know what he was in for when he signed up for the post, obviously.

Of course, once word gets out that an empty vessel is going back home the demons come hunting but luckily Sam (Jared Padalecki) and Dean (Jensen Ackles) are searching for Castiel after he escapes them and they arrive just in time to stop the demons from killing Jimmy/Castiel and his family. But when a demon possesses his wife, things change and the Winchester brothers and the former vessel fight to save them.

Meanwhile, Castiel had taken possession of Jimmy’s daughter who fights to save all of them as well and only as Jimmy is dying from a gunshot wound does he offer to become the vessel forever, saving his daughter from the torment and giving her a life to live – the ultimate sacrifice any good father would do.

More importantly than the character establishment of Castiel and his reaffirmation of being a worker for God rather than a worker for humans (or Dean has he points out), was the discovery by Dean that Sam has been drinking the blood of demons in order to get his heightened powers.

That leads to the end scene where Dean and Bobby (Jim Beaver) lock Sam away in order to, my guess, purge him of the demon blood in order to restore him down a path of the good rather than the path of evil he is currently following. Not sure if it is going to work as it looks like he gets a visit from an old friend and Ruby shows up again to give him another dose of the red stuff. It also appears as if we are definitely building toward the moment where Sam and Dean face off against one another because of it.

Dean is also going to be met with a choice which will probably bring us to the finale of the season where he either sacrifices himself, much like Jimmy did in this episode, or let the world succumb to the evils of Hell. And boy, what a ride that’s going to be.

Source: ifmagazine.com