Axel is a Bandit who appeared often in Paper Mario: The Jewel of Heart and Paper Mario: The Jewel of Soul. Goombenjamin says that Axel often steals stuff, but he's not a thief, which makes him an exact opposite of Swindell.
Axel first appears in Island Port City, where he gets seasick and ran past the Mario Brothers. He is next seen in the Dr. Koopert's General Hospital, where Dr. Koopert revealed to Axel that seasicknesses in Bandits are caused by a disease called a "Berserker", which is caused by a Green Virus. Mario and his partners go into Axel's body to fight the Green Virus, thus curing his seasickness. Next, he appeared in Roguetown where he meets his doppelganger, who is actually Robbie who joined Mario's party. He appeared later in Twilight City, where he gets turned into a Boo like the rest of the citizens. When he turns back into his regular self , he takes a dump by an accident, right on Boonita's stuffed teddy bear, making her angry. She then scares Axel away. He is later seen in Explo, where he slips on the banana peel, plus making a direct quote from The Powerpuff Girls Movie ("those are spreading bananas, far and wide!"). He is seen later in Starshift City, where Talen throws Axel out of the stage after flirting with her. After Chapter 7 is completed, he can be found standing on the dock in Island Port City. He remains there for the rest of the game, and will still be there after the game is beaten.
It's Axel. He followed us everywhere! As exactly as I thought, I heard that he's stealing stuff, but he's never been a thief. He likes to sweet-talk everybody, Right?