Poor Charlie. A rather alcoholic tailor from Pseudopolis, he spends most of The Truth, the only book he has appeared in so far, chained up and being pushed around by the rather distressing Mr. Pin and Mr. Tulip. And why?
Because he is a dead ringer for Lord Vetinari.
He is used in a rather ... interesting plot against the Patrician. Ultimately, he survives, and joins the Actor's Guild. Charlie is a kind-hearted fellow at bottom, if rather stupid. Given that Lord Vetinari has a maiden Aunt in Pseudopolis, one could conjecture that Charlie is an offshoot from the Vetiari family tree - hence his uncanny resemblance. Lord Vetinari's features are striking enough that they could easily be a family trait.
One can only guess at Charlie's future... at least until he's mentioned again.
'What have you done with Charlie?' said William.
Lord Vetinari looked at him in nothing but innocent surprise. 'Why, nothing. Should I have done something? ... I understand he's enrolled in the Guild of Actors, though of course I realise that there are those who would consider a deep dungeon a preferred alternative. I forsee a happy career for him, nevertheless. Children's parties, and so on.'
'What...as being you?'
'Indeed. Very risible.'
'And perhaps when you have some boring duty to perform, or have to sit for an oil painting, you'll have a little job for him?' said William.
'Hmm?' said Vetinari. William had thought that Vimes had a blank look, but he'd been wreathed in smiles compared to his lordship when Lord Vetinari wanted to look blank.