You will have to write around 6 case studies in your ethics paper therefore it is expected that you should have different introduction approaches for each case studies given.
Here we will discuss various types of Introduction approaches, before that we should see some key directions which you need to follow while writing your introduction.
You should not repeat the details and facts given in introduction, it has been an outdated approach to write introduction with just mentioning; stakeholder, facts given and values etc. It is clearly given in case study therefore it does not make much sense that you repeat these things in your introduction.
Your introduction must give some insight of the issue at the hand. You can briefly explore the key theme(it is one of the aspect of your syllabus).
The best approach comes from innovation, you need not to copy cat from others’ intro approach.