Assistant Agents help ordinary people about computer tasks, in many ways, thanks to their rational reasoning capabilities about the current model of the world. However they face strong acceptability issues because of the lack of naturalness in their interaction with users. A promising approach is to provide Assistant Agents with a personality model and allow them to achieve behavioral reasoning in conjunction with rational reasoning. In this paper, we propose a formal framework to study the relationships between the rational and behavioral processes, based on the expression of the behaviors in terms of influence operators on the rational execution of actions and plans.