Blair is regarded as the "Queen B" of the Upper East Side.
In Season 1 of Gossip Girl, Blair is introduced as the Upper East Side's beautiful and popular Queen B. She is dating Nate Archibald, and is best friends with Serena van der Woodsen. She also finds a close companion in Nate's best friend and her childhood friend, Chuck Bass, who becomes a partner for her schemes. When Serena returns home from boarding school, Blair learns from Nate that he lost his virginity to a drunken Serena over a year ago.Blair retaliates by publicly revealing Serena's connection to a rehab hospital. She then learns that the actual patient is Serena's younger brother, Eric, who had been committed after a suicide attempt. Afterward, a remorseful Blair reconciles with Serena.
After learning that Nate no longer loves her, Blair sleeps with Chuck, eventually falling for him. This leads to a heated affair and an eventual love triangle. Her inability to choose creates much of the first season's story line.She also begins a brief power struggle with freshman Jenny Humphrey. After she unites with Chuck and Nate in order to save Serena from the scheming Georgina Sparks, Chuck realizes that his feelings for Blair are real and suggests that they spend the summer together in Tuscany. However, he is discouraged by his father at the last minute, and stands Blair up.
At the launch of the second season, Blair was described by creators as the queen at the center of the Gossip Girl chess game.A large portion of her story line in Season 2 revolves around her love-hate relationship with Chuck Bass, which was labeled "the heart of GG" by People magazine. While competing with Serena, Blair forms an unexpected friendship with Jenny, who states that they each work for everything they achieve, while Serena often glides through life. During their interviews at Yale University, Blair and Serena apologize for their ill feelings and resume their friendship.
In the episode "O Brother, Where Bart Thou?", Chuck is devastated by news of his father's death, prompting Blair to offer her support while telling Chuck that she loves him. He initially shuns her advances, but later turns to her for comfort.However, the two stop seeing each other due to Chuck's uncle, Jack Bass, convincing him he has an inability to commit to a relationship. After being rejected by Yale, Blair finds unexpected encouragement from Nate. She is later accepted into New York University, and her competitive relationship with Georgina is eventually renewed.
As the season ends, Blair crowns Jenny the new queen of Constance Billard School. In the season finale, it is discovered that Blair slept with Chuck's uncle Jack and that Chuck had slept with Vanessa Abrams. Chuck then departs for Europe. He later returns to New York and reconciles with Blair while declaring his love for her, and the two finally begin a committed relationship.