After getting a call from Castiel that Eira and James were probably kidnapped by Shield. Let's just say Sam and Dean weren't happy.

Castiel had teleported and brought the Jotun with him. After fully healing him, Castiel had found out that he had an alternative form. Castiel had forced that form to appear and that's when they realized who he was.

Loki of Asgard, Odin's adoptive son. Castiel has told his brothers that Loki was still in  Critical condition. That he would have to stay behind and care for him.  Sam and Dean decided to drive to where they figure Shield would take there sister. They just were worried more about her because she was seven months pregnant. So Dean grabbed the keys to his Baby, his 1967 Chevy Impala.  Dean was ready for war. No one messed with his little sister.

While Sam and Dean were driving to a location in Illinois all the way from Kanas they knew it was going to be an eight hour trip...

Castiel was dealing with Loki's conditions,  his form kept changing back to the Jotun. He figured Odin must have cursed him. What the curse entitled was a mystery. Though Loki did seem to be in a coma until his body fully recovered. Castiel decided to make the environment colder to help heal him faster.