Growing up alone without his big brother Zigfried to play with, Leon grew up loving two things; Duel Monsters and fairy tales. He then wrote a letter to Maximillion Pegasus, asking him to make a series of cards based on the stories he loved to read. Pegasus granted his wish and made for him the Fairy Tale series, which became his main Deck. He then used this Deck to participate in many tournaments he won, including the Kaiba CorpGrand Championship.
The OCG/TCG version of the series revolves around the Field Spell "Golden Castle of Stromberg", making the deck very reminiscent of the "Umi" series. Most of them form small subgroups based on various fairy tails that interact more closely with each other then they do with the cards based on a different fairy tale.
"Golden Castle of Stromberg" comes at a steep cost of banishing 10 cards face-down from the top of its controller's Deck during each of their Standby Phases. However, this is diminished by the sheer versatility of its first effect: once per turn, in exchange for being unable to Normal Summon/Set any monsters during that turn, the controller can Special Summon from their Deck, any one monster whose card text specifically lists "Golden Castle of Stromberg". Unlike their anime counterparts, all of the monsters in series list "Golden Castle of Stromberg" in their card text, while their various effects they've had are updated to interact with the series Field Spell.
Iron John Group: Based of the fairy tail of the title character, "Iron Hans" special summons "Iron Knight" from the Deck whenever it is summoned. While the "Iron Knight" looses 1000 ATK if "Iron Hans" is also controlled by you, "Iron Hans" gains 1000 ATK for each copy of "Iron Knight" you control for as long as the series Field Spell stays on the field. "Iron Cage" is an interesting option for monster removal, while also helping triggering the effect of "Iron Knight" which searches "Iron Hans", or any Warrior monster provided the "Golden Castle" is on the field. The two monsters of the subgroup have potential not only for Link SummoningIsolde, Two Tales of the Noble Knights but also as an obvious Rank 4 engine, most notably the "Heroic Champion" Xyz Monsters.
Cinderella Group: "Prinzessin" has an effect that lets her search all the needed cards for her direct attack combo simply by being summoned while the "Golden Castle" is on the field. "Pumpkin Carriage" also protects the Golden Castle. "Glass Slippers" provide either a method for maintaining the advantage during the Battle Phase, or more fodder for "Isolde". "Prinzessin" and "Pumpkin Carriage" can also be used to summon "Aleister the Invoker of Madness".
"Hexe Trude" is the more-or-less the 'boss monster' of the series. Unlike most monsters of her Level, she can be Normal Summoned without Tributing if you have "Golden Castle" in your Field Zone and can not only destroy 1 card per turn, but if she does she can also declare up to 2 attacks on monsters during each of that turn's battle phases. This gives her a surprising advantage against most anti-meta cards (or, more accurately, cards that punish strategies that rely on special summon): "Trude" can bypass "Vanity's Fiend", "Vanity's Ruler", "El Shaddoll Shekhinaga", "El Shaddoll Winda" etc., which is necessary as most of the time the deck heavily relies on Special Summon.