I often wonder what makes people do it. I can understand liking the big brother/little brother feel of the show (either SPN or SG-1, or any buddy-type show that features one guy slightly older than the other), but...they're adults. In Sam and Dean's cases, they are young.

I suppose it could be that Dean probably (but we don't know to what extent) had a hand in raising Sam. I just don't buy Sam letting Dean call him kiddo, even if Dean maybe sometimes thinks of his brother that way.

Ah, well. I can't make people expunge it from their fanfic vocabulary, but I sure wish they would. ;)