This episode uses shapeshifters as a plot mechanic to allow Jack some closure. It reminds me of season 1's Skin using shapeshifting as a parable about domestic violence. The emotional material really works for the relationship between the Winchesters and Jack but it feels a little to coincidental that the case of the week ties in so nicely to the family melodrama.
I also must say I adore Collins as the Empty and that sequence is a highlight of season 13.
I also must say I adore Collins as the Empty and that sequence is a highlight of season 13.