One problem I had with this season is that they openly contradicted themselves at least a couple of times. The one that comes immediately to mind is Bobby’s ghost arc, in which they played up the fact that ghosts inevitably turn vengeful and violent and Sam even says (if I remember right) that there are no known “Casper” cases.
…except that just a few episodes ago, in 7x19 (‘Of Grave Importance,’) we met two helpful/protective ghosts, at least one of whom had been around for a very long time (and that’s not including Annie who had just died like a day before.)
And in 7x07, one of the ghosts was trying to warn people about the other, her murderous sister. In the same episode, Ellen gets a message to Dean via a medium to tell someone how badly he was hurting (as an aside, did anyone else notice that one of the brotherly psychic acts the museum curator mentioned was the Campbells?)
In 6x04, while not necessarily friendly per se, Gavin McLeod was perfectly rational and cooperative about giving Bobby dirt on Crowley.
In 5x09, the schoolmistress ghost was keeping the evil kid-ghosts from hurting people.
In 2x16, Molly had no interest in harming anyone and just wanted to know what happened to her husband and why some old geezer was chasing her.
And of course, in 1x09, Mary Winchester sacrificed herself to save her boys. (Granted, she did go after her murderer, Azazel—but she was hardly an irrational killing machine.)
Am I missing any? I bet I am.
Now I’ll grant you that none of these ghosts were ever full-time companions to the boys (or anyone else that we saw.) Not all of them were murdered, either. But still, it just somehow seems out of place for Bobby to go downhill so rapidly when there’s precedent to suggest that it’s not always inevitable, and when it was made very clear in 7x10 that he didn’t stay behind out of a burning desire for revenge on Dick Roman, but because he loved his boys and they needed him.