it makes me mad that it’s obvious Adam wasn’t ever supposed to be a big part of the show but then made it so he was in a way but then continue to ignore him 
the title of his first appearance was “jump the shark” which means introducing a character arch or a plot line that is ooc, maybe adds a new character that is new and younger or doesn’t make sense with the rest of the story. usually to try and make it as good as it used to be but usually signifies a downplay in quality or popularity. And having a third Winchester brother was exactly that.
of course the twist of the episode was that he was dead all along and it was kinda of “hah you were mad for no reason we aren’t going that route!”
But instead of keeping true to that they then reintroduced him and threw that away and made him the scapegoat for dean’s inescapable problem with the end of the world to end the show off so Dean could have a happy ending.
but when the continued the show they never went back and tried to fix Adam’s plot line because they chose to go back to the original plan of ignoring him again.
but what really makes me mad is that at a few points spn really did “jump the shark” or at least imo especially in the later seasons there are huge power jumps and they introduced characters like Jack. they have ooc plotlines (szn 8) and lose the dark vibe and feelings the show was built on. And it felt hypocritical to Adam
when supernatural decided to continue past season five they should’ve realized “right Adam we could have left him in szn 4 but we broght him back time to actually wrap up this character” and ik in like szn 7 or smth like that he was supposed to have a plot line and jakes agents got in the way but the show still went quite about him except for two mentions of him. even without being on screen the could have explained what happened more than they did especially when the actually went down to the cage. but instead they were mostly quiet about him till he finally was able to show up in szn 15
and i LOVE midam but i feel how they showed up out of the cage would not have been what happened if they had had the time or the care for these characters.
now i obviously love adam but the show should have only kept him for “jump the shark” OR they should have given him the chance to be a real part of the series, especially because without him the show would have been really different especially the end of szn 5.
im not saying he should have been a new main character along side sam and dean but also not have a ten year gap in between appearances 
