Dean's been a mess ever since Jack's birth. Not only was his mother locked in a parallel apocalypse world but also Cas was dead. On top of all that Sam insisted on keeping the freaking son of Satan under their roof. The only reason Dean agreed not to kill Jack was cause he knew he might be their only chance at getting Mary back.

Dean popped open a bottle of beer.

"I swear if you say Jack's family I'll friggin' punch you." He huffed, totally serious.

"He's Lucifer's son for crying out loud."