The application of complex dynamic systems theory (CDST) in second language (L2) research has recently gained ground, instigating a growing series of studies investigating the complex and dynamic nature of individual difference (ID) variables, such as WTC (willingness to communicate). Fewer dynamically informed investigations, however, have targeted L2 performance constructs, like speech fluency. Both WTC and L2 fluency presumably influence communications in a L2 and have been argued to retain cognitive and affective bases (Nematizadeh & Wood, 2019), rendering them likely to interact and influence each other during communicative events. Despite these, little has been done to address such dynamics, particularly from a complex dynamic systems (CDS) perspective. To bridge this gap, the present exploratory study employed an idiodynamic methodology, informed by CDST, to monitor WTC and fluency changes during three-minute, mainly monologic speaking tasks, with an emphasis on the dynamics of change in interaction with temporal measures of speech, including mean length of runs (MLRs), speech rate (SR), and pause phenomena. An investigation of 882 cases of interplay between WTC changes and fluent/dysfluent speech samples revealed an existing interaction, which took on four different forms. Results also indicated that the interaction is of a dynamic one, and is mostly two-way, direct and indirect, unpredictable, and interdependently multi-layered. Further, both variables as well as their interplay shared and exhibited such properties as dynamicity, nonlinearity, interconnectedness, and formation of attractor states, all of which are characteristic of complex dynamic systems.