From the Super Mario Wiki
“Heh heh heh! I'm pullin' another card trick today and makin' tons of loot! ...But somebody started tailin' me, so I came here to hide out for awhile. Don't tell anyone you saw me here...OR I'LL BOP YOU!!!”
Larson is a Bandit who defrauded Goomther with a fake credit card in Paper Mario: The Thousand-Year Door. After he performed this crime, he wished to continue criminal actions; however, after Goomther told the Trouble Center, Larson began hiding in the hidden alley of Rogueport alongside Darkly. Larson's dialogue is generally the same throughout the game, but after each chapter his ending phrase changes.
If the player takes Goomther's trouble, Mario and his partners have to chase Larson around Rogueport. (He is first found in his normal spot, though he respectively runs to Rogueport's harbor and its back alleys as the trouble progresses.) After catching him for the third time, Goomther will appear to enact revenge upon him. Strangely, Larson was seemingly never brought to official justice, as he resumed his position in Rogueport's hidden alley and even continued his crime-insinuating speeches.
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