I know that right in the middle of everyone writing for the prompt challenge, no one will have time or interest to adopt a bunny, but I want to put this out here anyway before I lose it again.
So, Sam does get his soul back in the end. And whoever gave it back to him adds a little bonus: Sam is restored without his memories of hell or what his body did in the meantime, unbroken and unaffected by his time in the cage - until the first time he falls asleep. Then it will all come crashing down on him and most likely leave him damaged beyond repair for the rest of his life. Dean, knowing this, tries to keep him awake as long as possible, but it's been a long time without rest and Sam is so tired...