Louis Grimaldi

Louis Albert Jean- Michael Grimaldi is Blair Waldorf's fiance and a Prince from Monaco. He is the son of Princess Sophie Grimaldi and the brother of Princess Beatrice Grimaldi.

Louis and Blair meet at the Musee d'Orsay in Paris at the beginning of season 4, where Blair is staring at her favourite painting by Manet. Louis approaches her (being a Manet lover himself) and asks her out on a date. Their short lived romance ends when Blair returns to New York, but she leaves Louis one of her shoes, stating "you can always come find me."

Towards the end of season 4, Louis arrives in Manhattan with Blair's show and they start dating again. They get engaged and leave for Monaco for summer together. Him and Blair are expeting their child but it is unsure if he's the biological father.