These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Yu Gi Oh The Thousand Year Door
Beam Me Up, Scotty!: The Queen's true form is never referred to as "Demon Chaos Queen" in the text of the story, only referred to as that in the notes where the card is put into OCG terms. The author has stated that this may not have truly even been a card in the physical sense, at least as far as her deck was concerned, but simply the Queen herself becoming part of the Shadow Duel.
Complete Monster: If any character in this fic fits, it's Lan'Tao. Not only was he willing to betray his mistress by cowardly striking Lyrius in the back, but for a thousand years, he kept himself alive through deals with two demon lords which required making Virgin Sacrifices of his own daughters (he reasoned he did it so that he wouldn't have to kidnap anyone who'd be missed) and if that weren't enough, made them into his undead slaves later. (His excuse for this was it saved money on hiring help.) The Queen was repulsed by him, as was Lyrius, who claimed that he was Mercy Killing his daughters when he killed them.
Missing Chapter: In the original fic, there is a chapter in which Stan duels Johnson of the Big 5 from the original Yu-gi-oh series which was only posted in a site called Pokemaster Forums, but is completely absent from the chapters posted on fanfiction.net.
Moral Event Horizon: The author has stated that the Queen's murder of Count Bleck was supposed to symbolize the point where she crossed this line, at least in the present day. (Andy's angry reaction to it was supposed to express it as such.)
Old Shame: Cyber Commander has regretted his "extra" Dark Scorpion cards, since they completely miss the theme of the Dark Scorpions (Five-Man Band), and the character of Wanda Underwood, as she's blatantly a repetitive, spiteful bashing of Weevil Underwood. He's since banned any other authors from using his Dark Scorpions and never used them again, and Wanda doesn't appear at all in Redux, her duels replaced with new characters.