Defoe’s heroines, Moll Flanders and Roxana, are in interesting ways a mixture of diverse Others. My aim here is to explore some of the ways in which these two heroines experience and embody alterity, focusing mainly on concepts of the self as a cell that generates doubles, pairs of identical mothers and daughters that are involved in constant battle with each other. More specifically, I would like to examine the mother’s self/body as a prison cell of the Other in Moll Flanders, and the urgency in Roxana to create a maternal self that becomes, what Homi Bhabha has termed, a hybrid third space that allows for difference to co-exist. Defoe’s early 18th-century mothers are in that sense a pre-echo of Bhabha’s basic thesis on alterity, as they also insist that otherness is internal and indispensable to the self. Inspired by Bhabha and borrowing from modern feminist theory—in particular, Luce Irigaray’s statements on placental tolerance of the other within—this essay will investigate the womb as an alternative/third space where otherness originates and where the boundaries between self and Other become so blurred that the notions of subjectivity and alterity call for a redefinition.