After a strong start out of the gate, Supernatural spend this episode laying the groundwork for this season's conflicts. The questions it raised are almost more important than what actually happened.
Since that does matter what happened however, in brief: the Leviathans make The Vessel Formerly Known As Castiel wade into a municipal reservoir. From there, they go out and and take over various people, preying on humans as all good Supernatural monsters do. One of them, posing as a surgeon, has the bad fortune to cross paths with sheriff Jodie Mills, who quickly figures out that something's wrong, and involves Bobby Singer. In the meantime, Sam's hallucinations continue to mess with his sense of reality. By the time the episode is done, Bobby is missing and the brothers are in an ambulance--Dean with a broken leg and Sam still tripping hard. What the ambulance crew doesn't know (but the brothers do) is that there's a nest of Leviathans waiting at the hospital where they're headed.
First, I have to say that it's always good to see Sheriff Mills. She once again proves to be a tough cookie in this episode, pulling a couple of badass moves even though she's recovering from surgery. (I think “Doctor Monsterface” is going to become one of my favorite epithets of the show.) The odds are against women in the world of Supernatural, so I really hope she sees the other side of this one. (Okay, in fairness, it's a dangerous world for everyone, but it seems to be particularly so for women.)
For the second week in a row, the show suggests that we've seen the end of Castiel. I honestly think that shot of his trench coat floating in the reservoir was intended to make people cry. Bobby directly addresses the potential emotional impact of this loss on Dean—but of course, Dean won't talk about it, because he's Dean.
In thinking over the possibilities, I realized what I wanted least: For Castiel to com back in another vessel-- female, white, thin, conventionally hot—and finally hook up with Dean. For the Destiel 'shippers, that would seem to be a cheap solution to the subtext created by the actors and played on mercilessly by the writers. For everyone else, it would cheapen the friendship itself. If another actor must be cast as Cas, what would be poignant would be for Dean to be so happy that his friend, his angel was okay that he paid no attention to the vessel. Whether you 'ship Dean and Cas or not, it's easy to see the poetry of a friendship between a mortal and an angel who ended decades of torment for him and saved him from the fate of becoming a demon. “I'm the one who gripped you tight and raised you from perdition.”
“Hello Cruel World” caused me to question once again to question Dean's wisdom in getting Death to get Sam's soul back. It really bothered me at the time, because once Sam found out the risks, he didn't accept them. (I'm still not clear on what was animating Sam if his soul was absent, but then, I haven't seen all of Season Six.) I mean, sure, it's terrible to think of Sam in the Cage—but he had told Dean to leave him there. The only way I can think to excuse overriding Soulless Sam's wishes is that he is a danger to innocent people, as we find out from flashbacks from his year with the Campbells. In fairness, though, the worst thing he did—attacking Bobby—he did to prevent a charred mess of a soul being forced on him. At one point, Castiel told Dean that if he'd wanted to kill Sam, he should have done it outright. As awful as that would have been, it was an option—and it's on that Dean considers in “Hello Cruel World”.
The friend that I watched Supernatural with last night suggested that perhaps Sam is still in Hell---that the writers, if they wished, could use that idea to reboot entire parts of the storyline, if they wanted to. I don't think they're going to do that—I think we see too much from Dean's POV for that to be what's happening. But I suspect that something similar may be going on. It could be that Sam's soul really is back on Earth, but that Lucifer really is there with him. I don't think he's free from this cage, or he'd be out doing his thing the way he did in Season Five; but I think it's possible that some part of him got grafted onto Sam's soul in the process of extracting it, allowing him to interact with Sam and only Sam. Yes, I know, it would be a very Harry Potter turn of events, but it wouldn't be the only parallel between Sam and Harry. It also seems like one of the few ways that anything could be done about what's going on.
At the same time, there are plenty of other irons to fry and fish in the fire. For one thing, how is Dean going to hunt with a broken leg? The brothers have come back from the dead plenty of times, but I believe this is the most serious non-lethal physical injury that either of them has had in several seasons. Hopefully Bobby is still out there, because they are going to need help, both in the short and long term.