<p>Advances in the development of flexible piezoelectric and thermoelectric materials have provided an important avenue for the exploration of energy scavenging through the thermodynamic-coupling of orthogonal energy-scavenging modalities. Hybrid thermo/piezo-electric generator devices (T/PEGs) based on flexible, layered, thin-film architectures, have shown a kind of thermodynamic entanglement of the piezoelectric and Seebeck effects in which the efficacy of the effects depend on each other. The hallmark of this coupled thermodynamics lies in the non-additive power generation characteristic of the combined effects. Thus, under some conditions, the power generation efficiency from such a combination hybrid device can be made to exceed that of its two components independently. In this work, we show that a basic coupled heat engine model can provide important insight into the origins of synergistic power generation. But, these models also suggest the emergence of other combined thermodynamic properties such as a <i>kinetically driven</i> Peltier-Caloric Effect (PCE) traced to Onsager reciprocity. We report the observation of this effect in T/PEG systems as a confirmation of this perspective of thermodynamic inseparability.</p>