It's not too difficult to feign total incoherency to avoid having to give an explanation for their presence and conditions. Castiel babbles a bit, making sure to fail to make eye contact with any of the nurses, and they stop asking questions pretty quickly.
He ends up in the psych ward, where he stays until the wee hours of the morning, falling asleep despite himself. After he wakes up around 3am, all it takes is a few small instances of "suggesting" to the hospital staff what to do and remember, and he's quickly wheeling Sam on a gurney through the parking lot in the dead of night, every so often glancing over his shoulder, looking for signs of pursuit.
Both of Sam's legs are covered in thick white casts and he bears bandages and stitches all over his body. What skin is uncovered is obviously badly bruised. But he's stable. He'll pull through.
He has to.
He uses the last of his slightly renewed energy to place his fingers against the forehead of a man in the parking lot and tell him to hand over his car keys, walk in the other direction, and forget the last few minutes. As Castiel hauls Sam into the vehicle, he knows this is sloppy and dangerous, but he's out of options. It's moments like this he misses his wings the most.
Fortunately, Crowley was… kind enough to deposit them at a hospital very near the bunker, and, banking on the fact that nobody just stumbles across the bunker, he just parks it right where the Impala is usually kept.
Hauling Sam inside is more taxing than he expected, and by the time he dumps him on the couch, he feels another long sleep coming on. When he wakes up, he feels the weight on his chest before he even recognizes his own consciousness, and once he identifies it, he wishes he were still asleep.
Reluctantly he rolls over on the couch to check across the room and see if Sam has woken up—hoping he hasn't, because he has no idea what he's going to say to him. He breathes a silent sigh of relief on seeing him still stretched out loosely on the couch opposite him, mouth hanging open, chest rising and falling steadily.
Castiel doesn't know what to do in the silent hours that follow. He finds himself wandering up and down the halls, regretting having Sam draw angel warding around Dean's body; if he could, he would wander into the room just to remind himself that that creature is a completely separate entity from Dean Winchester. For there Dean Winchester lies, peacefully asleep.
What sad times are these, when the only thing an Angel of the Lord can do to help even himself is kept out of his reach by scribblings on the wall.
He clenches his fists. There must be something, something he can do. No creature of heaven is ever completely helpless; only unimaginative.
Slowly the beginnings of an idea start to take shape in his mind.
Dean spends the first hour of the drive screaming in absolute fury.
Crowley's involvement, while a genuine surprise in the moment, has made it clear to him how he was found—the spell they used to locate Cain, when he got this thing on his arm in the first place. He deeply regrets not asking more questions about it at the time, because now, as far as he knows, there is nothing he can do to hide himself from it. There is nowhere he can run where they will not find him.
Fortunately he should have at least a little time, but that's the main object of his rage—that he failed to take care of the two only things he really has to fear right now. Sam was dead, but there is no reason to suspect Castiel hasn't brought him back by now.
He should have thought things through. Should have checked to make sure he could take out the angel before taking out Sam.
He was certain before that he couldn't go back to being that broken, worthless shell of a man again. But now, having done what he's done? He'd rather die, and in a very permanent sense.
The human Dean was too weak to handle something like this. It would destroy him. It would be kinder, frankly, to make sure he never sees the light of day again.
But Sam is too obsessively dependent on the guy to let a good thing be.
He finally manages to calm himself down enough to stop tearing up the car as he drives—he's hit the steering wheel so many times Kaden's hands are bruised, and early on he put his fist through the driver's side window. His knuckles are bleeding and the pain is definitely muted but annoying, and finally it occurs to him that now that Sam and Castiel have seen him, he should probably ditch this body.
Freaking just when he was starting to settle down in it.
He hops on into the only other person filling his car at the next gas station he stops at, and quickly withdraws, sliding back into the Impala and slamming the door shut. He sits there in his new body, a fortysomething man with a receding hairline and a fairly lengthy beard, and silently observes Kaden's prone form as he starts to stir on the concrete. Consciousness seems to rush to him suddenly—the realization of where he is, the pain in his hands, the vague memory of riding shotgun in his own meatsuit for the last few weeks, and he scrambles quickly to his feet, checking his pockets with increasing desperation.
Dean, not wanting to stick around to be asked for help, drives away without looking back.
Body hopping is a pretty entertaining way to fill the hours, but that gets old fast.
The fourth body is one he immediately thinks he could get comfortable in: a man in his early thirties—not too rickety nor baby-faced—definitely fit but not bulging with conspicuous muscle, his face decently good-looking but not identifiably so. The only problem is the hair. It's straight and seems manageable but long enough to partially cover his ears and Dean just can't see himself getting used to it.
He decides this is a good place to stay, and books a motel room for the night.
When he wakes up it takes him less time than usual to remember where he is and who he's riding, but there's something else distracting from all of that—an immediate itch that he can't reach, at least not now.
He has to kill someone.
But trying to find human beings who have it coming, at least in the moment, is getting tiring.
He suddenly remembers that he's come back into possession of an incredible arsenal collected for the sole purpose of killing supernatural entities, and books it to the car. Immediately upon throwing open the trunk he turns aside, cursing his brother under his breath, as well as the human version of himself—because even if he's able to get through these types of warding signs, it'll hurt like hell.
No. Not like hell. Not nearly that bad. He can handle it.
He eases his hand down into the weapons stash, and his arm starts to burn like holy water—just less acutely. Grimacing, he sifts around for several minutes, but the demon-killing knife is nowhere to be found.
Sam must have had it somewhere on his person. In the moment, when what he was after was about twice as large, it didn't occur to him to look for it. He groans in frustration and strikes the underside of the hood, leaving a depression in the metal the size of his fist.
Straightening up, he eyes the markings. He may be one of them now, but that doesn't mean he feels any sort of camaraderie or trust towards demons. If anything, they're even more against him now than before. So the question is… does he submit to going through that pain every time he needs to get into this trunk just to make sure his ass is covered, or does he scrub off the markings now and risk getting robbed?
The decision is pretty easy. He's not planning on going out of his way to do any hunting, and killing without weapons has proven to be an interesting challenge. He'll have little reason to need any of this equipment.
He slams the trunk shut and gets back on the road. Short term goal: find someone to kill. Long term goal: find the only weapon he'll ever need again. While avoiding demons and hopefully putting down his pain in the ass brother permanently somewhere along the way.
Hell if he knows how he's gonna swing that, but he's got time. He's got all the time in the world.