In this paper we desire to trouble various sites of borders, such as nature and culture, subject and object, and habits of thought and institutional structures. We will develop and elaborate an ontology of the in-between. Through a study of how beings and differences happen, we aim to disrupt and displace legacies of a substance ontology, with its substantive divisions between events and things, in order to encourage an event or concrescent ontology. We argue that the in-between is a continual, mutational happening, a reminder of the deep interconnectivity of what William James called “things in the making.” To disrupt the habits of thought and action sedimented by a substance ontology, we deploy four concepts: viscous porosity, corporal vulnerability, imporing, and anonymous agency. Our goal is to develop alertness to a dimension of in-between in which conscious connectedness happens without objectification.