Virtual characters simulated by computers have been a subject for research and development in both Artificial Intelligence in Education (AIED) and video game design. Between AIED and video games there is an emerging enterprise, that is, virtual characters in video learning game design. This paper proposes a Profile-Driven-Interaction (PDI) framework which borrows the design experience of virtual characters from AIED research to that for video learning games. The PDI framework enables virtual characters to take roles for various educational purposes based on the learner model of that learner and learner models of other learners. These virtual characters are designed in such a way that when they interact with a learner, the learner is actually improving her learning status. Based on this framework, a video learning game, called My-Pet-and-Her-Friends, is developed to address some relevant issues in the learning process, in particular, the issues of engagement and reflection of the learner.