Gaining Renown
Running an errand is a way to get in with the local guilds, For instance, working with William Makespeare and the Drip Monk is going to grant a point each with the Trades Guilds. There are additional ways. For instance, paying your permit fees grants you a point with the Praetorian Guard and having them treat you favorably would be nice.
Others like Vatha have needs that only a discrete set of individual with particular skills can handle.
As the party does favors for a faction, they advance in the ranks on a point system (1, 3, 10, 25, 100) and while they titles are honorary and sometime ironically applied by members of that faction, they also translate into favorable treatment by the factions. For instance, the Syndicate will grant better deal to a trusted "Receiver" and the Senate will grant citizenship and other privileges to those who play by the rules.