Heretofore has worked at the Patrician's Palace, and as a secretary. The fact that he did not work as a secretary at the Palace, where he worked as a gardener, is not known to his employer, Cosmo Lavish. His job is to acquire items from Vetinari for his boss, at considerable expense.
It is clear from his actions that Heretofore shares a modus operandi and an operating philosophy with Moist von Lipwig. While not in the same league as Moist and while not capable of the same degree of versatility, it is clear that Heretofore has seen his main chance in a single rich employer, who desperately wants to believe that the items he provides (at a suitable price to compensate for the risk involved in procuring them) have genuinely been acquired from Vetinari. To satisfy his employer and ensure the largest possible operating profit, Heretofore commissions a stygium signet ring, discovers who does the Patrician's laundry, uses a Palace contact to steal a pair of Drumknott's boots which he can then claim are the Patrician's, and finally has a sword-stick made, with a suitably lurid provenance, which he can then sell as Vetinari's.
So far, all this is showmanship of a sort at which Moist would be first to nod approvingly, but the maggot in the apple is Professor Cranberry, who insists on killing people afterwards so as not to leave anyone who could tell a story. Like Moist's reaction to Cribbins, Heretofore is deeply revolted and believes murder has no place in the life of a honest con-man. Yet greed (and fear of Cranberry) means he stays too long in Cosmo's service: Heretofore is last seen as the clerk in brown robes, leading his feverish and blood-poisoned master into the Presence at Moist's arraignment over the disappearance of a lot of gold. As Heretofore's actions and beliefs had a certain Lipwig-like style to them, one hopes he was still able to get away with at least some of the loot, with no Cranberry to hunt him down, and Cosmo incarcerated in the Havelock Vetinari Ward of the Lady Sybil Free Hospital...
Through a dialogue between Vetinari and Drumknott at the end of Making Money we learn that he is being sought by the Watch in Quirm after he bought a coach ticket to there but is more likely on his way to Genua. Vetinari wants a short clacks sent to "their man" in Genua but it remains unclear what his plans for Heretofore are. The Patrician hates to lose talented and resourceful people and there may be more impending projects than Moist von Lipwig can handle alone.