Randomly thinking about S4Ep19 Jump the Shark.
Kate knew about the life because that's how she met John. John didn't come around that much, but the fact his photo was on her nightstand tells me he visited more than just Adam when he came around.
Everyone but Adam knew about the life. Kate's home could've been a home base. Sam and Dean would have had a 'mother' and a home.
I feel like John missed an opportunity for a blended family.













