I will have to re-read it, but ISFP seems a bit far stretched. If anything, I would switch to INTP. I will think about it and try to deal with it later.Well, he slept with Liza and then regretted it. He didn't seem like the kind of guy who has a plan and I don't think he was sure about his ideas or what he was doing . Think about how he was talking about moving to another country but he suddenly abandoned this plan and ended up killing himself.
Thinking back to him, what was his motivation? He did not seem to be motivated by bringing his inner idea to life (Ji). He seemed more concerned with his internal imagery of things (Pi). He also seemed a bit hedonistic in the beginning. He's a rather unstable character, so he's hard to type.“if Stavrogin believes, he does not believe that he believes. And if he does not believe, he does not believe that he does not believe.”
I will go for very unhealthy INTP for now. Do you agree?