*Blair Flannigan, known as Rei Saotome (早乙女さおとめ レイ Saotome Rei) in the Japanese version, is a student and the only girl in the Slifer Red dorm. Initially a minor character appearing in a stand-alone episode during the first season, Blair joins the central cast at the beginning of the third after proving her worth as a Duelist.

In the dub, Blair takes on a Brooklyn accent beginning with her reappearance at the second season's conclusion (though she seems to lose it later on). During her Duel with Chazz she also made some egg puns ("that's no yoke", "eggcelent"). In the original, she refers to herself with "boku," a word for "I" typically spoken by young males, though its use by females is not unheard of. Though in the Tag Duel against Jaden and Alexis, when speaking to Jaden, Blair called herself "watashi", a significantly more formal personal pronoun that females often use. She did this in order to show her respect to Jaden, since she has a crush on him. She also refers to Marcel (Martin) as "Marty" in the original. She has the tendency to make references to the fact that she is a Maiden in Love.

When she was first introduced, she wore a standard Slifer Red jacket and boots with gray pants ending at the ankles. To hide her hair she disguised herself as a boy, she then wore a clip with both a large hat and an orange bandanna. When Blair returned near the end of season 2, she was once again disguised, since she still used her bandanna and wore a kabuki mask. She now wore a sleeveless orange shirt under a dark blue and aqua version of the Obelisk Blue jacket with blue jeans and lilac boots. Starting from season 3, Blair's main outfit consists of her orange shirt, a Slifer vest, black shorts with a slanted brown belt, black socks that went slightly above her knees and newly designed Slifer boots. She continued to wear this outfit even after she became an Obelisk.

In the first season, Blair was a shy, love-struck but highly intelligent young girl. She had an insane crush on Zane, but switched to a crush on Jaden by the end of her first episode. She has aced perfectly on all her entry exams and was almost ranked to Ra Yellow.

When she returned near the end of season 2, she kept her crush on Jaden but grew up greatly became much more developed, much more mature and even developed a sort of leadership role as evidenced when she's Marcel's boss of some sort. She was also willing to work with Hassleberry to get photos for the yearbook.

Blair's initial deck is a Love deck focusing on "Maiden in Love", using it to take control of enemy monsters and turn them against their user. She further uses support for the Maiden like "Cupid's Kiss" and "Happy Marriage" to optimize this strategy.

During the Genex Tournament, Blair uses a Mystic deck. The deck's full mechanics are not explored, but it seems to revolve around summoning monsters by the effect of "Mystic Egg" and using "Mystic Revolution" to evolve them into powerful high-level forms.

In Season 4, Blair uses a Token deck, relying on summoning Monster Tokens.*