I interviewed with Pacific last month and it was really casual! The writing prompt is really straightforward and open ended, so there is no wrong answer. You will be given two prompts and be asked to write about one. The interview is with one faculty and one student, but there is no stress factor since it is a closed interview, so both of them are just trying to get to know your personality. As long as you are enthusiastic about the profession and genuine, the interview should go really well. Hope this helps!