Samuel Vimes has come a long way since he was born in a small flat in the Shades, the poorest part of Ankh Morpork. He is a descendant of 'Stone Face' Vimes, the man who executed the last King of Ankh Morpork and never shrugs that off. He joined the Night Watch in his early 20s, when he first donned Vimes' famous boots. Throughout the series, even when he is made Commander and forced to wear proper boots, he claims that in his old pair he could find his way around the city, just by feeling the type of stones underneath his feet. During his first 25 years in the watch he raised to the rank of Captain, but at the same time the power of the watch diminished. The streets were instead ruled by the the Thieves' Guild and the Assassins' Guild, who made sure no one was robbed or killed by a non-member.
Vimes' life changed forever during the course of Guards! Guards!. A new member, Carrot Ironfoundersson came in to the watch from the dwarf mining villages in the Ramtops. His serious attitude and perfect morals made the Watch turn around. They actually started arresting people and upholding the law. Carrot appealed to Vimes' sense of justice.
During the events of Guards! Guards! Vimes and his Night Watch protected the city from the returns of dragons to their dimension. Carrot proved himself to be the true King and heir to the throne of Ankh Morpork, but he would never admit it because everyone knows that kings are bad. Vimes, at the end of the book, "Men at Arms", marries Sybil Ramkin, one of the richest women in Ankh Morpork and becomes a Duke, a title he has never accepted. Lord Vetinari, patrician of Ankh Morpork also makes him Commander of the Watch, which offends Vimes' hatred of authority. He does however take the title in an attempt to turn the watch around and do some good for the City.
Vimes' hatred of authority and wealth, along with his belief in justice make him completely incorruptible. He is also a complete cynic of human nature, and can identify criminals easily ("at the end of the day, everybody's guilty of something"). Vimes is one of the few people in Ankh Morpork who is not speciesist. He hires Trolls, Dwarfs, Undead, Gargoyles, Werewolves and even a Golem on to his team, to the dislike of the Patrician.