I was going to make this an end note for my fic Dependency that I just posted, but I wanted people to be able to read it without these opinions of mine affecting their enjoyment of it, so I posted it separately. If you'd like to read the fic, it can be found
here.
Honestly, Sam's self-sacrificing plan for saving the world in the fifth season by hurling himself into the pit has always irritated me. Surely they could have found a better solution. I saw where the writers were going with it, with Dean finally recognizing Sam's sovereignty, accepting that he's a grown-up who can make his own decisions, but I thought that was a really lame "first adult decision" for Sam to make, and I also felt like Dean suddenly recognizing Sam as an adult came out of the blue in the series.
I actually started this story with an idea of writing about Sam going to a 12-step meeting for his demon-blood addiction. I thought it might even end up being humorous, but then it took me in a completely unexpected direction, filling in what I saw as the gaps in how that transformation from Sam as kid brother to Sam as an equal to Dean came about, and I liked it! It filled in a lot of gaps I perceived in the series--how Sam was dealing with his addiction during the 5th season after the 14th episode, the whole issue with whether his powers and the way he got them was a good or a bad thing (since Dean et al help him drink demon blood to make him strong in the 5th season finale), etc. This was my way of bridging some things that didn't come together in a way I found satisfying in that season.