what purpose is served by bringing in minor characters such as Mr. Wolfshiem and Mr. Klipspringer, "the boarder"?

The two men make us question Gatsby's truthfulness.......... they fill in the background for us, even if that only serves to make us scratch our heads about who and what Gatsby really is. Who is Klipspringer, and why does Gatsby shelter him......... Wolfshiem on the other hand, his character supplies further information about Gatsby and also supplies us with historical; Meyer Wolfsheim was a notorious criminal noted for fixing the 1919 World Series........ Gatsby knew Daisy before the war.