The axes of the default Dynamic Concept Cloud (DCC) are set to display the maximum variance between terms. This causes major related concepts to form clusters which (roughly) represent the most prominent conversations in the data and dictate context for a particular concept within a discussion.
You can change the shape of the DCC by clicking and dragging terms, or by setting a topic as either the X or Y axis. Drag a concept to the upper left quadrant (or to any outer edge) and related concepts will follow. This exercise helps isolate discussions so you can visualize major themes around a concept.