That "Solid Snake Method" sounds a lot like the emacs doctor...
In case you don't know what the emacs doctor is: It's an easter-egg of the text-editor emacs (it is, however, mentioned in the manual). The doctor is a chatbot based on ELIZA, and meant to portrait a psychotherapist. Since it is a rather simple script, it is very limited in what it can do, and mostly just reformulates user input as questions.
I'd go with different system acounts. That way their savegames are guaranteed to stay separate.
That's because on PC most games just care about the system user when determining the savegame folder, and don't care about steam accounts.
So, what I'd do is to: