Mr. Tuxedo Pants is the cat owned by Charlie Lima. He moved into Fiona Coyne's apartment with his owner when they were left homeless. He currently lives in a cage in the art gallery since Charlie does not have her own residency, and her mother won't allow Mr. Tuxedo Pants to live with them.
In Paper Planes (1), he makes his first appearance. The former roommate of his owner kicked them out of their apartment when they could not afford to pay rent, leaving them homeless. He moves into Fiona Coyne's penthouse with Charlie. He likes to lounge on Fiona's bed. Fiona thought that she got her rashes from being allergic to him, but it was really bedbug bites.In Paper Planes (2), Fiona realizes she isn't ready to be in a relationship with Charlie, so her and Mr. Tuxedo Pants have to move out. They plan to move back into Charlie's mother's house. As Charlie said, "Mr. Tuxedo Pants and I always land on our feet."
In Take a Bow (1), Charlie reveals that her mother kicked Mr. Tuxedo Pants out of her house, so he has been living in the art gallery in a cage. Fiona offers to take care of him for a few days, saying he would be at home and that she could use the company. When she asks Charlie to prom, he meows, which the two take as a sign of agreement toward the matter. While Holly J. is talking with Fiona, he can be seen sitting on Fiona's bed. Later, during the time Fiona is drinking and crying, she holds Mr. Tuxedo Pants, saying she doesn't deserve him or anyone else. She then pushes him out onto the fire escape, setting him free into the streets.
In Take a Bow (2), Fiona tells Charlie that she set Mr. Tuxedo Pants free, which infuriates her. To try and make it up to her, Fiona hangs up missing pets signs for Mr. Tuxedo Pants around the city, but Charlie informs her that he had already been found. Fiona later tells Holly J., Anya, and Chantay that she set him free, and they all burst out laughing.