Not P but DFW: a plot thing

[Mike Jing]

The following excerpt is from David Foster Wallace’s *The Broom of the
System*, Chapter 5, Section a:

Was this a religious thing? A deterministic crisis? I had had a friend . . .
No. Determinism would be fine if she were able to feel that what determined
her was something objective, impersonal, that she were just a tiny part of
a large mechanism. If she didn’t feel as though she were being used.
Used.
Yes. As if what she did and said and perceived and thought were having some
sort of . . . function beyond herself.
Function. Alarm bells. Dr. Jay, after all. *A plot thing*?
No, not *a plot thing*, definitely not *a plot thing*, she wasn’t making
herself understood.

What does "plot" mean here?