Bless your heart is a useful Southern parlance which can convey any range of meanings from genuine sympathy to outright contempt.

4 minutes ago, JamesSavik said:

Putting Southern parlance into your writing is tricky. If it's authentic, to non-Southern speakers it might be incomprehensible. If you use a more regional dialect, like Acadian/Cajun, it can be as incomprehensible as Swahili. Maybe, it's Brylcream and just a dab will do.

 

I remember watching Justin Wilson, the Cajun chef, on PBS. It was the first time I heard Cajun dialect, which is odd. We had a lot of property around Baton Rouge and went there frequently when I was a boy.