An unlicenced thief. He lost his Thieves' Guild licence for un-necessary enthusiasm and conduct unbecoming in a mugger and, when encountered in Men at Arms, is desperate and unheeding enough to follow Angua von Überwald into an alley without asking exactly why a vulnerable-seeming young woman is confident enough to walk down a dark alleyway in the Shades on her own, by night.
Five seconds later he finds out, and all thoughts of mugging her are suddenly lost in a desperate attempt to get away. It is possible that the Trousers of Time are at work here, and he falls down a leg which may have been fated for Carrot in a different phase of the Multiverse, as he eventually dies, after some intervening adventures, in a freak accident involving an ant-eater. (compare the text of pages 21 and 105 of the Corgi paperback edition and consider a possible outcome had Carrot chosen to turn back and follow Angua down that alleyway, perhaps out of a misguided attempt to be a gentleman and walk her home).