  We present three distinct types of models of dark energy in the form of a
scalar field which is explicitly coupled to dark matter. Our construction draws
from the pull-back formalism for fluids and generalises the fluid action to
involve couplings to the scalar field. We investigate the cosmology of each
class of model both at the background and linearly perturbed level. We choose a
potential for the scalar field and a specific coupling function for each class
of models and we compute the Cosmic Microwave Background and matter power
spectra.
