Can someone explain to me why Crowley would think that the Alphas know more about Purgatory than Demons or Angels?
I think Samuel might come gunning for Dean now that the chances of getting his daughter back have been eliminated. Of course I think Crowley had a backup plan and is actually inside Samuel or Sam.
Clearly Angels and demons don't access Purgatory.
Humans when they die naturally are taken by Reapers to Heaven or Hell. Reapers and Death seem to have no direct access to Purgatory either.
Now humans can be transformed into Monster in a few ways. We have none since season one how Vampire's reproduce, we have known how Werewolves reproduce, and since season two we know that spirits are souls that Reapers can't take. Either from choosing not to let go, or being anchored to a single location (which is what happened to Mary).
When monsters die they go to purgatory. Thus Crowley believes that Alpha's (monsters) might have some knowledge about Purgatory as that is where their kind goes upon death.
Now I assume (based on what happens to Demons, corrupted human souls) that if you are killed by the colt or by Sam, you are utterly destroyed as those souls don't seem to ever come back.
For example Azazel would still be around in Hell (and thus able to return).
I assume the monsters that have been killed by the colt (such as a two Vamps) are utterly destroyed thus they don't exist in Purgatory.
And just as Demons have access (though its extremely difficult before the gates were opened) to Earth, and Angels have access to Earth (apparently easily.
Crowley assumes that at some point in time some monsters would have managed to access Earth from Purgatory. And since the Alpha's have been here the longest they would most likely have that knowledge if it happened.
Another question, since Crowley can't access Purgatory, Samuel might be trying to find a soul that no longer exists. Since Mary was a spirit, she would should go to Purgatory. But what if she was utterly destroyed like Missouri said?