Blue Hour is a Cardfight!! Vanguard fanfic written by author Digidramon on Fan Fiction Dot Net. The fic follows a similar plot format to the Vanguard anime, following a rookie fighter, Robert Macmillan, as he is motivated by a defeat at the hands of Samuel Wilson to attempt to make the shop team. Joined by Agatha Gladstone and Charles Bannerman, Robert attempts to fight up to the ranks of the Vanguard Nationals.
Digidramon has since continued the story with two more fics, Fallen Sun, a short story focusing on the characters of Team Bright Dawn, and a sequel, Midnight Sun, dealing with Team Avalon a year after Blue Hour as they clash with the mysterious Team Midnight Sun.
Midnight Sun was discontinued, but Digidramon has moved on to what was intended to be its sequel: Setting Sun, set in the same universe, but focusing on a new main cast composed of Seth Abbott, Sophia Ayers and Tahir El-Amin.
- The Ace: Samuel and Gabriel. Tahir in Setting Sun.
- Breaking the Fellowship: The early plot of Midnight Sun, with Team Avalon being divided after losing to the eponymous team. Ends with Putting the Band Back Together with some help from Team Excalibur.
- Catapult Nightmare: Seth has a dream like this in Chapter 7 of Setting Sun, though it's downplayed.
- Darker and Edgier: Blue Hour was relatively light-hearted and down to earth, all things considered. Midnight Sun, on the other hand, routinely demonstrates how horrifying Melanie's Psyqualia is, has the heroes broken within the first ten chapters, and has a much darker feel as a result.
- Dark Is Not Evil: Samuel and Agatha, who run Shadow Paladins and Pale Moon, respectively.
- Deconstruction: Midnight Sun picks apart the idea of trying to change a corrupt system from within. Team Avalon genuinely want to dismantle the system that rigs competitive Vanguard in the interests of its corporate sponsors to give everyone a fair chance at the championship, but because they themselves have benefited from the system and waited until they had done so enough to resolve their personal problems (Robert's mother and Joel's brother) before acting, they're considered hypocrites and regularly pilloried by the press.
- Equivalent Exchange: Samuel's personal philosophy is that to achieve your goals, you have to sacrifice something.
- Gladiator Games: The Phoenix Colosseum Clan.
- Jerkass: Charles and Gabriel.
- Late-Arrival Spoiler: Fallen Sun and Midnight Sun both spoil that Team Avalon became national champions at the end of Blue Hour. The latter also spoils the ending of the former when Luke and Mary show up.
- Setting Sun is written as though Midnight Sun was finished, with the fact that it, well, wasn't dealt with by Digidramon offering a synopsis of the unfinished portion to anyone who asks. This does however mean that it spoils certain plot details from Midnight Sun's intended endgame, with Samuel using Dragruler Phantom as one dropped offhandedly in chapter 3 and the dismantling of the corrupt system as another.
- Kill It with Fire: Alice and Gabriel, who both run Kagero decks. Also a notable aspect to Joel's Arena Master Phoenix Feather.
- You Have Outlived Your Usefulness: Samuel's Shadow Paladin deck is notably focused on the sacrifice aspect of the Clan.
- The Worf Effect: Often, given the focus of the fics, though most notably Team Avalon themselves become the Worf in the early chapters of Midnight Sun, losing to the eponymous team to demonstrate Midnight Sun's power and Melanie's Psyqualia.