Fernando de Rojas liked to create characters in pairs, to help build character development through relationships between complementary or opposing characters. In the play in general there are two opposite groups of characters, the servants and the nobles, and within each group are characters divided into pairs: Pármeno and Sempronio, Tristán and Sosia, Elicia and Areúsa, in the group of servants, and Calisto and Melibea, Pleberio and Alisa, in the group of nobles. Only Celestina and Lucrecia do not have a corresponding character, but this is because they perform opposite roles in the plot: Celestina is the element that catalyzes the tragedy, and represents a life lived with wild abandon, while Lucrecia, Melibea's personal servant, represents the other extreme, total oppression. In this sense, the character of the rascal Centurio added in the second version is an addition with little function, although he has something to do with the disorder that calls the attention of Calisto and causes his death.