In the comic series PLOP, there were quite a few characters in one-shot stories I would have liked to see more of. A handful of them did have a much later second story in PLOP.

Here's the first 6-page "Comic Book McFiend" story from the fanzine AMAZING WORLD OF DC COMICS, issue 6, June 1975:
https://scans-daily.dreamwidth.org/93482.html

The complete AMAZING WORLD OF DC COMICS 6 issue here:
https://view-comic.com/amazing-world-of-dc-comics-issue-6/


An issue dedicated to editor/artist Joe Orlando, who began DC's Mystery line of comics, along with PLOP and SWAMP THING, the Fleisher/Aparo Spectre run in ADVENTURE COMICS 431-440, among other milestones.
And Joe Orlando was previously one of the EC artists in the 1950's glory days of EC. There were a lot of great unpublished stories and covers in this Orlando tribute issue.
Also included was the story "Judgement Day" by Orlando, possibly the single best story EC ever published, that I already posted in a Pre-Code comics stories topic.
Plus an interview of Orlando, and an overview of his career and accomplishments, particularly at DC. Orlando even did covers and other art for TIME and NEWSWEEK.

Among the other great features in that AMAZING WORLD OF DC COMICS 6 issue is this story with "Comic Book McFiend", a kid with mountains of comics and an all-powerful genie like mentor/friend, with powers that are a variant of Billy Batson/Shazam.

This was a rejected story from PLOP, that I was suprised otherwise never saw print except in this obscure form. I thought it was a very enjoyable story for one rejected. Which is odd, and obviously others liked it too, at the very least among DC's editorial staff, because a sequel to it saw print in PLOP 24.

To my knowledge the only two appearaces of the character.