Captain Morgan, known as "Axe-Hand Morgan," earned that nickname the hard way—his right arm is literally replaced by a massive steel axe. He's the first high-ranking Marine we actually see in the series, and he makes quite the impression.
Physically, Morgan is intimidating: tall, white-blond hair, a steel jaw, and he's usually smoking a cigar. Like other top Marine officers, he rocks that oversized billowing coat. The axe is hard to miss, though interestingly, he didn't always have it. Three years before the main story, he was slimmer and still had both hands, though his general look was pretty similar otherwise.
He commands Shell Town's naval base, but "commanding" is generous—he rules through fear and corruption, squeezing the islanders for taxes and executing his own men if they step out of line. The power clearly went to his head. Before his promotion, Morgan seemed like an actual brave soldier, but success and authority twisted him into what he is now.
His son Helmeppo is cut from the same cloth, equally awful at throwing his father's rank around to bully people. Morgan barely acknowledges him as a son, even saying Helmeppo's worthless. There's zero fatherly affection there.
Morgan's obsession with rank really shows during his fight with Luffy. Despite getting absolutely nowhere—taking hit after hit without landing a single blow—he refuses to admit defeat. His pride won't let him lose to some rubber kid.
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