A narrative note

Endnote 127 of Infinite Jest says a lot in a little. It's a brief bit about how the extraneous details in the description of Lord's Triggering Situation in the game of Eschaton are Hal's own additions. The note itself reads: "A lot of these little toss-ins and embellishments are Inc amusing himself, not Otis's [sic] TRIGSIT, which is 100% all biz."

You could say that this implies that Hal is Infinite Jest's narrator. But then you'd need to explain why, in an endnote that he must be narrating, Hal refers to himself in the third person. Instead, given what we've got in this note, a better argument is that Hal is the editor of a bunch of retellings and recollections.

In this editorial scenario, the book consists of pieces written by the individuals that they feature. These individual pieces are then submitted to Hal, who in turn adds little "toss-ins and embellishments" and puts them in order. Though I'm not familiar with Byzantine erotica, Hal is apparently deeply interested in it. This interest definitely suggests that Hal has edited Infinite Jest since the book's plot - the actual sex and eventual climax -  is left until its end. The pre-plot part of the book, with its developing characters, side plots and settings, is really just foreplay, after all.

Ultimately though, in this editor Hal scenario, David Foster Wallace himself had the final say, and left notes as he saw fit.