a season 12 fixit baby!jack AU where jack's born a baby, and dean and sam are left with the responsibility of raising him, but unlike the usual cas being resurrected in a few months, it takes a good number of years.
dean has gone completely insane after losing cas (also lucifer falls through into the apocalypse world but mary doesn't so that sideplot can die), and even tho he hates jack at first, he is the very personification of Mother Syndrome so he takes care of him and ends up insanely attached to him. he thinks of jack as his. his and cas'. but his. it's all borderline uncomfortable, but also endearing because dean is a good caretaker and jack is a literal baby who needs said caretaker. and then cas shows up and dean's little world is off-kilter (again) and he's jealous and happy and sad and still a little insane because of all he's lost, but then they settle into this awkward domesticity for a while and there's a lot of emotional turmoil going on in dean's head but then he eventually starts letting hismelf sink into it all and then it's just *throws glitter in your face* FLUFF!