Leon reveals his motivation to duel, stemming from being ignored by his family in favor of the smart, highly gifted and talented Zigfried. To distract himself, Leon became engrossed in fairytales, and started dueling following the creation of a set of fairytale cards. He initially believed this was earning Zigfried's respect, but in reality his older brother saw him as little more than a tool for destroying KaibaCorp. Determined to earn his elder brother's love, Leon plays an illegal Field Spell: The Golden Castle of Stromberg, which infects KaibaCorp's systems with an extremely powerful and dangerous computer virus that rapidly deletes the files and can't be destroyed by card or trap effects.