Kim Chang is doing time for defrauding her boss as payback for sexually harassing her. Confident and smart, Kim is a survivor. She is what is known as a ‘gate gay’ – a straight woman who is gay while inside.
Kim is Franky Doyle's on again off again girlfriend. Kim and Franky have an open relationship. Kim gets transferred to another block during season 2 to further her studies per request of Franky. Kim goes on to be paroled at the end of Season 2. Kim goes to see Franky in season 3 to give her some money. She then returns to Wentworth and is assigned to cell block H6 for violating her parole. Chang admits to Franky that life outside is tough; her advances towards Franky, however, is rejected so she suspects that Franky and Bridget Westfall are having a sexual relationship, to which she responds to by lashing out at Bridget.
After being rejected by Franky, she felt hopeless and became involved with the Asian crew led by Tina Mercado, spending as well a period of a serious drug addiction at the beginning of season 4.
From season 4 on Kim is moved from a main character to a secondary one, serving only as a background inmate.
After Franky comes back to prison in season 5, the two of them will basically never interact again until episode 5x10, when Doyle asks to borrow a mobile phone illegally owned by the Asian gang. After a brief and soft jealousy argument, Chang will later lend the telephone to Franky, showing both that the there is no animosity between them anymore and that they still care about each other, despite interacting just occasionally.