I remember reading this fic a while back - I don't think it was ever finished - but the basic premise is both John and Dean get annoyed with Sam being more sensitive than them and they both say some harsh words. Sam takes it upon himself to toughen up and promises himself that he'll never cry again. I remember they hunt a werewolf (or something similar) and both John and Dean get hurt, leaving Sam to kill it. Sam ends up with Pastor Jim (I think) who is shocked so see Sam so cold and emotionless and refuses to let John and Dean see him. I remember there was a scene near the end where Sam tells Jim everything that happened in a church with John and Dean listening in.