Leo is cheerful, prone to making jokes—sometimes at inappropriate times—and uttering quips he believes "fire up the team" as expressed in “Origami Tsunami”. His persistently carefree nature causes him to possess an airy quality and he enjoys spontaneity. It's also said in the first episode of the series that humor is how he manages to cope.
Leo has confidence that usually turns into arrogance and his brothers, Mikey, Donnie and Raph are often annoyed by his lack of humility. He still loves them