Slaves in Plautus's The Pot of Gold (called Aulularia in Latin) are far smarter than their masters and often carry out tasks that the masters are not savvy enough to accomplish. For example, Staphyla, Euclio's slave, is savvier and more intelligent than Euclio. At the beginning of the play, she wonders why her master has become so erratic in his behavior, and she worries, "Nor can I tell how best I can conceal his daughter's state." Staphyla knows that Euclio's daughter, Phaedria, is pregnant, and Staphyla cares for Phaedria when her father is not aware of his daughter's condition.
Another slave, Strobilus, who belongs to Lyconides, outwits Euclio, a miser who jealously guards his pot of gold. Strobilus knows that he must do the work for his master, who wants to marry Phaedria (and who has made her pregnant). Strobilus says in Act IV, Scene I, "The slave who wants to serve his master well/Does first his master's work and then his own." Strobilus overhears Euclio speaking about where he has hidden the gold, and then Strobilus steals the gold. His efforts allow Lyconides to return the gold to Euclio and to marry Phaedria, so it is Strobilus who manages to get his master what Lyconides wants.
As is typical of Roman comedy, several of the major characters in The Pot of Gold by Plautus are slaves. The slaves serve many different purposes in the plot and the audience experience. Like the rustics of Shakespearean comedy, the slaves are often among the funniest characters in the play, most prone to physical comedy and slapstick, and also providing much of the singing and dancing that were part of the comic spectacle.
Next, Strobilus plays the part of the "servus callidus", or clever slave, who is an entertaining contrast with the innocence (and slight dim-wittedness) of the young lovers. Throughout the play he schemes to buy his freedom and eventually fails, something that the Romans found funny. Another classic piece of Roman humor is the subplot of slaves trying to avoid being beaten but ending up getting the beating anyway (this is not something we now would find funny -- but the Romans did).
Both Staphyla and Strobilus assist the young lovers in reaching their goal of marriage.