According to Umbrella Academy creator and writer Gerard Way, Mr. Pennycrumb was intended to look like artist Gabriel Bá's dog. However, the puppy was inserted into the comic in too much of a hurry to make him look quite right. In Hotel Oblivion, Mr. Pennycrumb is to be redesigned to look like a pug.
While on a walk with his adoptive sister Allison (The Rumor/#00.03), The Boy detailed for his sister what he had experienced before returning to the family. The narrative The Boy shared was intense and dark, yet he still took notice of the puppy. Viewing a number of puppies in the front window of pet store Barks, he commented, "That's one cute puppy."
Thereafter, Mr. Pennycrumb accompanied The Boy practically everywhere (except in battle). This included the restaurant Wok n Roll later the day he was purchased, back to the assassination of President Kennedy. Upon returning to the present, Mr. Pennycrumb got the ice cream that the rest of the Umbrella Academy would not eat.
Mr. Pennycrumb is a standard puppy, meaning he has the powers of adorableness on his side