Walter Hardy was a notorious art thief who went under the alias of Black Cat. His style was to implant his stolen art with isotopic trackers which he hid all across New York. He also fathered a daughter, Felicia whom knew of his true nature but did not want her following in his footsteps as a thief and criminal.
Eventually, Hardy crossed the Maggia - the powerful New York City mob and he and his family were made a target. Hardy was eventually captured by the police and he was imprisoned in Ryker’s Island for several life sentences. Knowing Felicia would be in danger whilst he was still alive, Hardy faked his own death in a supposedly failed escape attempt, remaining on the low radar for decades.
Posing as Detective Mackey, Hardy contacts Spider-Man to meet him on the roof of an NYPD building with the story that he is retiring soon and needs his help closing the cold case of the Black Cat’s missing art. Hardy uses Spider-Man as his muscle to track the hidden art across the city and reclaim it; whilst learning about his daughter’s career as the new Black Cat and Spider-Man’s relationship with her.
Once Spider-Man successfully locates all of his art, Hardy vanishes from NYPD. When he returns looking for Detective Mackey, an officer informs him that such a detective does not exist and he realises he has been played. Contacting Spider-Man for a final time, Hardy asks him to watch out for Felicia, confident that he will not tell the police, the Maggia or his daughter about him being alive on the basis that he’s a nice guy.
Despite being a notorious thief and criminal, Walter Hardy is not an immoral man. He never killed anyone in his career and cared about his family, not wanting his daughter to follow in his footsteps and sounding both saddened and impressed over her career as the Black Cat and her upgraded gear.
Like his daughter, Hardy has a fondness for Spider-Man though obviously not in the same, flirtatious way Felicia does. Rather, he has more of a high respect for his character and ethics, even calling him a nice guy and a worthy choice for his daughter.