Hunted by the World Government for his lineage, Ace ultimately met his end two years before the current storyline after being captured and sentenced to death, which resulted in the Battle of Marineford in an all out clash of powers. Ace was freed, but he sacrificed his life to protect his younger brother from Admiral Akainu.
Although they were not blood related, Ace looked remarkably like his foster brother, Luffy. However, Ace was more serious looking than Luffy's lighthearted design, and was also slightly taller and more muscular. He also sported rather childish freckles (inherited from his mother), and tended to make an skeptical facial expression by raising his left eyebrow. Interestingly, his facial features were almost akin to his biological father Gol D. Roger in his youth without his mustache.
Ace's tattoos were among his most remarkable, trademark features. He had a tattoo on his back of the Whitebeard symbol — purple bones formed in a cross behind a purple skull with a white mustache — that he described as his pride and joy. Ace had another tattoo on his upper left bicep that spells "ASCE" vertically. The "S" crossed out is a tribute to Sabo as that's his jolly roger. On the cover of Chapter 596 indeed, Ace's tattoo is written as "ACE" instead of the original "ASCE" as the cover is a "what if" image of Ace, Luffy, and Sabo together as adults with the latter being still alive.
Ace wore an open-front shirt until he received Whitebeard's tattoo - afterwards, he stopped wearing anything over his upper body except when on winter islands. He wore black boots, black knee-length shorts with an eyelet-studded orange belt, and a blue pouch belted around his left leg. He also wore a short second belt with a large red "A" on the silver buckle over his right hip, but left it unfastened and threaded the free end along the back of his shorts. A dagger in a green sheath hung at his left hip. On Ace's left arm, he wore a Log Pose and a red and white striped bracelet around his wrist, an orange elbow guard, and his "ASCE" tattoo. He wore a red beaded necklace and an orange hat with two blue smileys, one frowning and one smiling, and a string of red beads sitting above the rim. Two long orange side straps hung down sides of his hat and met at a large medallion of a bull's skull with orange tassels.
Unfortunately, Ace lost his trademark hat, which he already had when he began his journey as a pirate, on Banaro Island as a result of his duel with Blackbeard. His knife was also apparently confiscated, as he no longer had it in his next appearance as a prisoner at Impel Down. The tattoo upon his back that he took so much pride in was later destroyed by the same blow that eventually led to his death. However, at his grave, Ace's hat and knife were placed at his tombstone either they were retrieved, or they were duplicates in Ace's possession.
During the ending credits in the second movie, Clockwork Island Adventure, previews of upcoming characters from the Baroque Works Saga were featured. Ace was also included amongst the many characters, but while his clothes were almost identical, he boasted a very different color scheme to the one he was given in his official appearance in the anime.
As a child, Ace is shown to have often worn t-shirts with two-kanji phrases on the front (such as "innocence" and "violence"). On some occasions they are linked to the scene in which they were worn, like "independence" when the three brothers built their own tree house to live in. He often wore knee-length shorts and a black elbow guard on his left arm. Ace was always seen wearing dark brown, flat, slipper-like shoes, and in the winter, he wore a green cardigan over his normal clothes.
Ace was much more intelligent, polite, and generally more bearable than Luffy, which prompted the Straw Hat Pirates to question whether he was truly related to their captain. While several people who knew Gol D. Roger noted Luffy is quite similar to the late Pirate King, Whitebeard himself claimed that Ace's personality was not at all like his father's. It seems that among the very few things the brothers shared was their recklessness as pirates (and their near-bottomless stomachs). In addition, Ace liked to party as much as his brother does. When he boarded Buggy's ship, he was drawn by the smell of food and decided to enjoy himself while he was there. Ace could be a bit vulgar though as he once used a woman's skirt to wipe his face while he was dining at Spice Bean in Alabasta.
There were two running gags about Ace. The first was his rather extreme narcolepsy. He tended to randomly fall asleep while eating and conversing, leaving strangers around him wondering if he had died. This was first seen in Alabasta when they thought he died in the middle of eating. The second was that he did a "dine and dash" routine wherever he went. This went back to his younger days with Sabo and Luffy, when they would often dine and dash in the city of Goa.
His "politeness" is due to Makino's teaching after Ace asked her how to introduce himself to Shanks (being his brother's savior).[20] Before that, Ace was rather cold and rude to anyone he was not familiar with.
As the son of Roger, he lived in his shadow and is to date the first D. depicted to truly question his own right to exist, while displaying the fewest commonly seen D. related traits. Ace seemed to have lifelong problems dealing with his parentage, even after denouncing Gol D. Roger and accepting Whitebeard as his only father. This was in direct contrast to Luffy, who accepted his father's identity immediately upon learning it and did not seem to care when he was told how dangerous of a man he was. However, Luffy did not grow up with knowledge of the identity (or even the existence) of his father. Ace believed that it was natural if he were to really die as nobody in the world wanted the son of the devil (Roger) to live. Ace commented upon his own death that he had never sought fame or fortune - all he had wanted was the answer to his lifelong question of whether or not he should have been born, as this was the only thing preventing him from dying with no regrets as he and Luffy had vowed to do so and the fact he had a younger brother to look out for. Ace's only regret was that he would not live to see Luffy achieve his dream, which he believed Luffy undoubtedly would accomplish as he was his little brother.
Ace had a tendency to never back down from a fight, saying that he would never run once facing an enemy. Because of this, some people believed that Ace had a death wish, but in truth he wanted to prevent people he cared for from getting hurt. Dadan stated that he inherited this tendency from his father, Gol D. Roger, despite loathing him. While Ace emerged victorious over enemies he refused to run from, such as Porchemy and Bluejam, his stubbornness hurt him on a number of occasions, particularly when he refused to back down against Blackbeard or Admiral Akainu.
Ace was also easily provoked by and became violent towards anyone who insulted or harmed people close to him. In one of Garp's conversations with Curly Dadan, this was revealed to be a trait of Roger as well. During his childhood, Ace had a tendency to severely injure anyone who insulted Roger, though he himself disliked his biological father. After hearing about Sabo's presumed death at the hands of a World Noble, Ace quickly became bent on killing the Noble and Dadan had to pin Ace down and tie him to a tree to stop him.
Ace's temper got the better of him, especially in cases when Whitebeard, proclaimed by Ace to be his only father, was insulted. Believing that this was the case when Blackbeard broke the iron rule of the Whitebeard Pirates and fled after murdering a crew mate, Ace pursued his traitorous subordinate despite his crew mates' efforts and even Whitebeard's orders to stop him. Ace later came to see that his stubbornness had gotten him into the ordeal of being scheduled for execution. Even though he managed to escape death on the scaffold thanks to the pirates' and Luffy's efforts at Marineford and was well on his way to freedom, Admiral Akainu got to him by insulting Whitebeard. Ace quickly turned back to face him, ignoring his crew mates' warnings to not become angered over Akainu's provocations. Unwilling to let him get away of speaking ill of Whitebeard, Ace attacked him out of fury only to have his arm burned by Akainu's Devil Fruit powers. Akainu then took the opportunity to attack Luffy on the sideline, leading Ace to jump in, sacrificing his life to shield Luffy from the attack. While saying his last words, Ace sadly admitted to Luffy that he (Ace) wasted away all of his efforts to rescue him.