Every character ever played by Chevy Chase is Fletch undercover.
God knows what he's investigating as Pierce Hawthorne.- Fletch chose aliases he thought would resonate the person he was speaking to. Particularly the Stanwycks (Alan's parents), who reminisce at how great a president Harry Truman was; Babar, because the doctor was fat, grey, and dry; G. Gordon Liddy, because the mechanics would be blue-collar Republicans; Ted Nugent, because Stanwyck would have grown up with 70s hard rock.
The films take place in the same universe as "Animal House"
When Fletch storms in on the lodge meeting honoring their "Man of the Year," the award is going to one Fred Dorfman. That's the name of Flounder's older brother in "Animal House" — a film, incidentally, in which Chevy Chase was originally going to be cast as Otter. A role that eventually went to Tim Matheson. Who plays Alan Stanwyk in "Fletch."
