Commander Sir Samuel Vimes' entry in the Discworld Companion is as follows:Head of the Ankh-Morpork City Watch. Badge No. 177. An upright and honest man whose appointment to the despised Night Watch - regared by all sensible people as a completely useless appendage to the running of the city - may have been the cause of his drinking problem. But is has also been suggested that he is in fact naturally more sober than other people (to put it technically, he is slightly knurd).Since that was written, Sir Samuel has been given the title of Duke of Ankh. This was also against his will, but Lord Vetinari got him to accept the rank with something approaching blackmail.
A state of acute sobriety is not one in which a man would like to view the society of Ankh-Morpork and he naturally sought to ameliorate this with a drink or five, and got the number wrong.
It is known that he was born in Cockbill Street in the Shades, that his father was Thomas Vimes and his grandfather Gwilliam Vimes. Membership of the Watch was a family tradition and Samuel would have joined shortly after leaving school had he ever gone to school.
Vimes never got the hang of ambition and worked his ay sideways rather than up, and his promotion to Captian was simply the result of the sheer unthinkability of promoting any other watchman.
By his own account he was a skinny, balding, unshaven collection of bad habits marinated in alcohol, although these days he is better shaved and doesn't drink. Partly as a result of this latter fact, he is morose, cynical and ridiculously - and to his own embarassment - soft-hearted in certain circumstances. He is almost certainly one of Nature's policemen; it has been said of him that his soul burns to arrest the Creator of the universe for getting it wrong.
He loathes kings, and hates undead and assassins. He is also unashamedly speciesist - he deeply dislikes trolls and dwarfs, but in an almost proprietyroial way, so that he has risked his life and badge to defend them merely so that he can continue to dislike them. He hates the city in the same way; it's his to hate. Married to Lady Sybil Ramkin, he was promoted to Commander, and knighted against his will, by the Patrician.
Sir Samuel has been made temporary ambassador to Uberwald (The Fifth Elephant) and generally is an extremely useful tool for Lord Vetinari. He has been dubbed "Vetinari's terrier" - a nickname which, although inaccurate (Wuffles is Lord Vetinari's terrier) is nonetheless appropos. Vetinari knows how to push his buttons (and when to stand back and let him run loose) to get him to do what he wants. Consider the following excerpt from Feet of Clay:'I couldn't let our gallant policeman know I'd worked it out for myself, could I? Not when he was making such an effort and having so much fun being...well, being Vimes. I'm not completely heartless, you know.'Vimes is immensely useful to Vetinari - he does as second nature the things which the Patrician's position will not allow his Lordship to do personally. Although Vimes hates Lord Vetinari, he has a certain respect for him ('he's honest - honest like a corkscrew') and knows that the city is better off under him than many of the past Patricians, or (Gods forbid) a king.
'But, my lord, you could have sorted it out diplomatically! Instead he went around upsetting things and making a lot of people very angry and afraid--'
'Yes. Dear me. Tsk, tsk.'
Ah,' said Drumknott.
'Quite so,' said the Patrician.
'May I make an observation, my lord?'
'Of course you may,' said Vetinari, watching Vimes walk through the palace gates.
'The thought occurs, sir, that if Commander Vimes did not exist you would have had to invent him.'
'You know, Drumknott, I rather think I did.'