Louis Grimaldi is a guest character in the Gossip Girl TV series during its fourth season. Louis becomes entangled in Blair Waldorf's life and is infatuated with her, instantly falling for her in the Musée d'Orsay. Blair suspects him to be a Monégasque Royal though no further information regarding his royal affiliation is discussed. Their short-lived romance ends as the summer slowly dwindles and Blair returns to New York. But soon Louis came to Manhattan, and they start relationship. At the end of season 4 they engaged and go to Monaco for a summer together.Louis Grimaldi is portrayed by Hugo Becker.
A shy romantic at heart, Louis a really hot guy is pleased to find out that he shares the same interests as Blair such as Manet. Louis was not cautious at first with regards to his date with Blair and until he sets up a double date in a Prince and the Pauper scenario to see if Blair is genuinely interested in him. Shocked that Blair has shifted his interest from him to his driver when he set him up to be a royal, he ends the date, disappointed that Blair was just another woman chasing him for his royal title. He shows himself to be forgiving when he gives Blair a second date. The date goes well when he sees a lighter side to Blair, who still lies about her interests but is clearly infatuated with him. He seems to be very observant when he found out that Blair is an American and a New Yorker just by looking at her watch, which was set at Eastern Standard time. His observance also contributed to his discovery of Blair's interest in a Manet painting.
During a summer stay in Paris, Louis meets Blair at the Musée d'Orsay, at first reluctant talk to her but gathers the courage to meet her. Blair fulfills her Parisian dream of meeting someone who shares the same romantic interest as she does and states that she loves the Impressionist artists and says that her interest should have emboldened him, since he should already know that she is a romantic. Louis and Blair converse and asks about her American roots. Their conversation is interrupted when Louis' driver saying that the embassy is asking for him and mentions the word Grimaldi. Blair expresses her interest about the mentioned words and Louis sets a date with her.
Louis sets a double date and Blair arrives when he picks her up, disappointed that he's driving his own car but even more disappointed when Louis states that he is the driver and Jean Michel, who is his driver, is the Monagasque royal. The date grows uncomfortable as Louis' preference for simple commoner pleasures clash with Blair's value for elitist tradition. When Serena chases after Blair when she leaves the date, Blair returns happier and Serena arrives soaked in fountain water. When Jean Michel goes after Serena, Blair decides to follow him and Louis reveals his set-up. He states that he wasn't cautious at first until Jean Michel advised him to be. He reveals himself to be the real royal and ends his date with Blair, disappointed.
Blair gets a second chance at a date and the two have a conversation across the Seine River. Louis is surprised that Blair likes kababs and subway musicians (which she isn't obviously interested in) and invites her to a ball. Blair gladly accepts until news of Chuck haunt her. Serena arrives at Harry Winston to inform Blair of Chuck's plan to leave Paris.Then she leaves with Serena to keep Chuck from leaving towards London and convinces him to return to New York.
Blair eventually decides to end her stay in Paris and goes back to Musée d'Orsay. Louis hoped she would come with him to a ball again and when informed of the news of her decision to return to New York, he persuades her to stay. She tells him that she can't keep using him and her stay in Paris to hide from her life in New York. He asks if they'll ever meet again and she hands him the expensive shoe she is wearing to remember her by. Blair comically leaves the museum with only one shoe.