Chen Jin was born in Hebei province but moved to Nanjing, JiangSu at the age of 10. The Nanjing dialect, which is one of many dialects of the wider Mandarin, is spoken in most part of Nanjing. WSX is from Suzhou, JiangSu. Suzhou dialect is a variety of the Wu language, which is not Mandarin. But I do not know what dialect or language WSX and CJ would converse in. Perhaps someone from JiangSu can enlighten us.