The relationship between the main protagonist and captain of the Straw Hat Pirates, Monkey D. Luffy, and a former member of the Seven Warlords of the Sea, Donquixote Doflamingo, is characteristic of how Eiichiro Oda interweaves character relations in the vast creation that is One Piece.
Contrasting Personalities and Motivations
Basically, Luffy and Doflamingo are two forces that are at two extremes of the One Piece world. The quotient of Luffy being steadfast and inseparable, with the addition of his dream to become the Pirate King, decidedly keeps him far away from Doflamingo's arrogant, proud, psychopathic disposition. This kind of contrast in the personalities between the characters lays the foundation for their rivalry.
It would be a difficult challenge for Luffy because of the kind of complex personality Doflamingo is, who is given to theatrics in words and an attitude that is always light. His manipulativeness and careless disregard for other people's lives contrast radically with Luffy's straightforward approach to dealing with situations and deep caring for his friends and allies.
The Dressrosa Arc: A Pivotal Confrontation
Their relationship comes full bloom in the Dressrosa Arc. It has shown just how their conflict is, along with Luffy's resolve to defeat Doflamingo by his own hands. The arc underlined the depth of cruelty to which Doflamingo had come and the actual extent of his influence, thus putting more meaning into Luffy's mission to defeat him.
This arc pits Luffy against Doflamingo himself and the convoluted political situation that dresses up Dressrosa. The battle is no longer as simple as it used to be: it now includes an entire kingdom and its people, hence adding more elements to their confrontation.
Leadership Styles and Crew Dynamics
An interesting parallel between Luffy and Doflamingo can be made regarding leadership styles and loyalty. While Luffy captures real affection and loyalty from the Straw Hat Pirates through action and character, what the crew of Doflamingo's—so-called Donquixote Family—does is something quite different.
While his crew cares for him and his goals, it is still obvious that at heart, they fight harder to achieve his objectives. If compared with the Straw Hats' dedication towards Luffy, the dynamic of their relationship is much more complex and even manipulated.
Impact on the One Piece World
This battle between Luffy and Doflamingo reflects on nearly every main event that happens in the One Piece world. Luffy's victory over Doflamingo not only saves Dressrosa but also upsets the power balance in the New World. The event increases Luffy's status within the piracy world as one of the biggest throne holders and enhances his reputation globally.
More than that, the fallout from this battle has even more to reveal of the political nature of the One Piece world. Ties between Doflamingo and the underworld, along with information on the "National Treasure" of Mariejois, really flesh out the greater story of the series.
Ethical Contrasts and Moral Dilemmas
This arc between Luffy and Doflamingo also features the size of the scale of morals that might possibly exist in the One Piece world. Some of Doflamingo's actions arguably stand as one of the most evil acts in the series, from manipulating an entire kingdom to his cruel treatment of others. This puts sharp contrast to Luffy's morals and selflessness to help others, which goes to the very core of what One Piece means.
The epitome of conflict, contrast of ideologies, and events with far-reaching consequences, such as that between Monkey D. Luffy and Donquixote Doflamingo in One Piece, is a case itself. Their confrontation makes up the Dressrosa Arc, one of the most central moments in the series, giving meaning to what character development really is and just how complex the dynamics of power plays out in this world of One Piece.