The nature of humans interacting with interface characters (e.g. embodied agents) is not well understood. The I-PEFiC model provides an integrative perspective on human-character interaction, assuming that the processes of engagement and user interaction exchange information in explaining user responses with interface characters. An experiment using the Sims2 game was conducted to test the effects of aesthetics (beautiful versus ugly, as engagement factor) and affordances (help versus obstacle, as interaction factor) of interface characters on use intentions, user engagement, and user satisfaction. Results of the experiment showed that (1) people tended to use helpful characters more than obstructing characters, (2) user engagement was enhanced by beauty and perceived affordance of the character whereas (3) intentions to use the character were not affected by good looks, and (4) the most satisfied users were those that were engaged with the character as well as willing to use it. This stresses the importance of enhancing affordances so to increase user engagement with interface characters. The I-PEFiC model provided a valuable framework to study the (interdependent) effects of relevant factors in human-character interaction.