  We propose a new model of scalar field dark matter interacting with dark
energy. Adopting a fluid description of the dark matter field in the regime of
rapid oscillations, we find that the equation of state for dark matter is
non-zero and even becomes increasingly negative at late times during dark
energy domination. Furthermore, the speed of sound of dark matter is
non-vanishing at all length scales, and a non-adiabatic pressure contribution
arises. The results indicate that there are still unexplored possible
interactions within the dark sector that lead to novel background effects and
can impact structure formation processes.
