Based on Support reply, there are rules which images will represent the articles. We should make sure that every character have image matching this rules and this image is actually used for both categories and the related pages functionality. And complain if they wouldn't.
Seems to only really apply to things parents can buy for their kids and EGS Vol#1 and Vol#2 is apparently not in stock in any physical bookstores. Also, no web comic wikis have a Parent Page although some web video wikis have one.