About Portgas D. Ace
Portgas D. Ace, born as Gol D. Ace and nicknamed "Fire Fist" Ace, was the captain of the Spade Pirates before being recruited into the Whitebeard Pirates and becoming its 2nd division commander. The biological son of the late Pirate King Gol D. Roger and Portgas D. Rouge, Ace was put in the care of Monkey D. Garp and Curly Dadan after Roger's death, which is where he became the sworn brother of Monkey D. Luffy and Sabo. Due to Roger's absence from his life, Ace disowned his father and took his mother's surname, ultimately declaring that his captain Whitebeard was his true father.
Ace's pursuit of his former subordinate Blackbeard for the murder of their crewmate Thatch led to him being captured after their duel on Banaro Island, and he was turned in to the Marines, who held a public execution for him on Marineford due to his heritage; this triggered the Summit War of Marineford. While freed from bondage, Ace would ultimately die at the hands of Admiral Akainu while protecting Luffy.
Ace's death proved the final catalyst following the Straw Hats' defeat at Sabaody that would make Luffy put his crew's journey on hiatus so they could all train for the next two years and return powerful enough to survive the New World on their own, paving the way for the second half of the series. His reincarnated Devil Fruit would eventually be consumed by his sworn brother, Sabo, ensuring that his will would live on.
Ace first appeared at the end of the Drum Island Arc, but was only formally introduced in the Arabasta Arc, where he acts as a brief ally of the Straw Hat Pirates. He is a central figure during the Summit War Saga. He is also the protagonist of Ace's Great Blackbeard Search cover arc.