Monkey D. Luffy is the central protagonist of the film One Piece: The Desert Princess and the Pirates: Adventures in Alabasta. He serves as the captain of the Straw Hat Pirates. His background includes having accidentally eaten the Gum-Gum Fruit, a Devil Fruit that transformed his body into rubber, granting him immense stretching abilities but costing him the ability to swim. He grew up in Foosha Village and was inspired to become a pirate by the pirate Shanks, who gave him his signature straw hat as a promise for their future meeting.

Luffy's personality is defined by a cheerful, carefree, and fun-loving demeanor. He is highly optimistic and possesses a great ambition to become the King of the Pirates by finding the legendary treasure, the One Piece. He often follows his instincts and has a huge appetite, frequently thinking with his stomach. Despite his seemingly simple-minded nature, he demonstrates a sharp, intuitive understanding of people and situations when it truly matters. He becomes serious and fiercely aggressive when his friends are threatened or when he is in battle, but he never holds grudges and approaches fights with a sense of adventure.

His primary motivation during this story is to help Princess Nefertari Vivi save her kingdom of Alabasta from the civil war orchestrated by the Shichibukai, Sir Crocodile. Luffy does not seek personal gain or glory for this mission; his driving force is his loyalty to Vivi, whom he considers a friend, and his desire to stop Crocodile's evil plot. This reflects his broader motivation to protect his crew and those who have earned his trust.

Luffy's role in the film is to lead the Straw Hat Pirates into the heart of the conflict. He takes on the strongest opponent, Crocodile, while the rest of the crew handles the high-ranking Baroque Works agents. His actions are pivotal: he volunteers to distract Crocodile to allow Vivi to escape, and he is the one who ultimately defeats the villain after a grueling battle. He is the primary driving force who refuses to retreat or give up, even after suffering a severe defeat and being buried alive in sand.

Key relationships within this story include his deep, unwavering bond with his crew members, each of whom he trusts implicitly to handle their assignments. His friendship with Princess Vivi is central; he fights not for her kingdom or her title, but for her personal safety and happiness. His antagonistic relationship with Crocodile serves as the film's climax, with Luffy adapting to overcome the Warlord's sand-based powers. He also has brief but significant interactions with Nico Robin, who initially works for Crocodile but later saves Luffy's life, beginning a shift in her allegiances.

The Alabasta arc represents a notable point of development for Luffy. It is one of his first major confrontations with a Shichibukai, a powerful member of the Seven Warlords of the Sea. His initial defeat at Crocodile's hands forces him to re-evaluate how he fights and to find a creative, life-threatening solution to counter Crocodile's ability to desiccate objects. This victory cements his growth from a relatively unknown pirate into a recognized threat, leading to his bounty being raised. The experience also deepens his commitment to his friends and reinforces his role as a protector, even for those who are not part of his crew.

Luffy's notable abilities in the film are derived entirely from his rubber body. He uses a variety of Gum-Gum attacks, such as Gum-Gum Pistol for long-range punches and Gum-Gum Gatling for rapid flurries. His most desperate and innovative technique against Crocodile involves using his own blood to create sticky fists that can bypass Crocodile's dry sand defenses, demonstrating his ability to think outside conventional limits. He also possesses immense physical endurance and a stubborn will, allowing him to continue fighting long after most would be incapacitated.