Feeney Upshot is the sole watchmen of the Shires in the beginning of Snuff. He is an awkward and naive young man who Sam Vimes believes is about 17-years old. Initially, as the constable of the Shires, he wears no formal uniform, has no helmet, carries no warrant card, does not understand how to arrest anyone and believes that he must follow the magistrates directions rather than the law. Until he is put straight by Sam Vimes, he is used by them for their own evil ends; smuggling, slavery and murder. One of these ends is to try to pin the 'murder' of the blacksmith on Vimes, which is the point where he comes to Sam's attention. Once he falls under the tutelage of Sam Vimes, he quickly realizes what being a policeman is all about and becomes an exemplary officer, redeeming himself fully in Sam's eyes. Both his father and grandfather were Constables in the Watch and he was given the inherited position and its truncheon inscribed with "LAW" after his father retired when he could not live with himself for inaction in the murder of the goblins three years before.
As well as being a policeman, Feeney's grandfather had spent time as a sailor, during which time he brought back his grandmother Ming Chang from Bhangbhangduc. Feeney learned a number of things from her including her native cuisine, of which she became locally famous, and martial arts. He taught Sam Vimes the move "He Up Down Very Sorry" by example. His grandfather helped him nurture his ability to "read people like books" by taking him with him around the Shires, introducing him to people, and telling him their stories. Because of this, he was able to make a very educated guess as to whether a person was telling the truth or not and to have some insight into their character.
Until the events of Snuff, he has led a very quiet life as a policeman so he devotes his time to pigs and uses the lock up for a pen, which explains its pervasive smell even through the disinfectant used to make it ready for Sam Vimes. His prize pig is a monstrous-looking boar he affectionately calls Masher, whose father was a wild boar that crept in from the woods and coupled with Masher's mother when she was in-season. Though Masher is clever and shows a doggish loyalty and obedience to his owner, he is regarded with considerable fear by the locals, and Chief Constable Upshot makes use of Masher in much the way a more urban watchman would make use of a large, viciously loyal dog. Few of the Shire's residents would think of arguing with the Chief Constable if the possibility of Masher slipping his chain is hanging in the air.
He lives with his grandmother who has a very strong streak herself - protecting her grandson and his prisoner from the mob who try to break into the lockup. By the end of Snuff he is confidently taking charge of the Watch in the Shires, hiring Jethro the Blacksmith as a constable and giving him a cardboard badge (its a start).