Patches is introduced as a charming and polite dalmatian. He seems to care about others but his facade cracks whenever people fail to be taken in by his charm. His true personality is one that is vengeful, spiteful, lonely and violent. He takes whatever love he can get and lashes out at anyone who fails to serve him. While much of the cast views Patches as a simple sociopathic murderer, there is reasoning behind his actions. He is incredibly lonely and overcompensates for his lack of self respect by being toxically defensive. He also used to be Angel's boyfriend, before he killed him in rage.

The voice should like Kevin Michael Richardson's performance as the Joker, both deep and psychotic. 

Voice reference: (1) Kevin Michael Richardson as The Joker - YouTube