Monkey D. Luffy is the protagonist of the anime/manga series One Piece and the love interest of the pirate Empress Boa Hancock.
Luffy is the teenage captain of the Straw Hat pirates. He has the power to stretch his entire body after eating the cursed gum-gum fruit, though he can't swim as a result. His lifelong dream is to find the One Piece and become King of the Pirates.
Hancock originally has an antagonistic relationship with Luffy in the Amazon Lily Arc. Later, upon witnessing his innocent and selfless nature and noticing that he did not judge her even after knowing of her past as a slave, she develops strong romantic feelings for him. Her time with Luffy changes her personality considerably. She has a demure behavior when she is around Luffy showing that she loves him. She has a hard time looking Luffy in the eye, tends to blush in his presence and daydreams about him. Her love for Luffy caused her to turn against the World Government on several occasions.
During the Battle of Marineford, she states that all men, both marines and pirates alike are her enemies. However, when Luffy arrives she focuses her attention on protecting him. She defends him from Smoker and the Pacifistas and becomes furious and yells at anyone that tries to hurt him. After the battle, she helps hiding a wounded Luffy at Amazon Lily until he recovers and expresses her desire to be the one to take all the suffering in Luffy's place. She cares so much for Luffy that she barely eats any food on her return to Amazon Lily until she was sure that Luffy was alright.
Hancock is very loyal to Luffy despite his rejection of her idea of marriage and not having the same feelings to her. In his turn, Luffy also protected Hancock by declaring he would not tell Magellan how he broke into Impel Down even if it killed him. At Marineford, he showed his gratitude by hugging her and remarking that she had saved him twice, both in helping him break into Impel Down and giving him the key to Ace's seastone handcuffs.