  The two component model of neutron star dynamics describing the behaviour of
the observed crust coupled to the superfluid interior has so far been applied
to radio pulsars for which the external torques are constant on dynamical
timescales. We recently solved this problem under arbitrary time dependent
external torques. Our solutions pertain to internal torques that are linear in
the rotation rates, as well as to the extremely non-linear internal torques of
the vortex creep model. Two-component models with linear or nonlinear internal
torques can now be applied to magnetars and to neutron stars in binary systems,
with strong variability and timing noise. Time dependent external torques can
be obtained from the observed spin-down (or spin-up) time series,
$\dot{\Omega}(t)$.
