Lheureux is the cloth merchant of Yonville who sells Emma on credit, unhurriedly finances both of her affairs and, in the end, collects the debt that leads to the seizure of her goods and to her suicide.
He comes on the stagecoach that carries the Bovarys to Yonville, but he only enters the scene in chapter 5 of Part II, with a box of dry goods. Emma buys nothing, and he does not press: "there's no hurry, whenever you like." Then he takes charge of Hippolyte's wooden leg, orders from Rouen the dagger Emma wants to give Rodolphe and, the next day, presents a bill for two hundred and seventy francs, when all the drawers of her desk are empty. For the escape, Emma orders from him a cloak, a trunk and a travel bag.
In Part III the debt climbs a step per chapter. In the midst of mourning for Charles's father, he suggests the power of attorney; he sells curtains on credit; he makes Emma sign four bills of one thousand francs each and, out of the two thousand difference, hands over only eighteen hundred, because the banker Vinçart kept two hundred; finally, a summons arrives for eight thousand francs within twenty-four hours. When Emma tells him "Never mind morality!", he replies that it is "a thing that never does any harm," and, faced with her pleas, he ends with "I don't have to lose any sleep over it!" and shuts the door. After her death, he goes back to pressing Charles through Vinçart.
Lheureux follows both affairs from start to finish, from the agricultural show, where Rodolphe begins his courtship, to the bills that pay for the Thursdays with Léon. His credit works like Rodolphe's speech: it promises that nothing costs anything now and charges later, with interest, and it is the debt, more than the guilt, that closes the siege around Emma.