  When pulling a particle in a driven granular fluid with constant force
$F_{ex}$, the probe particle approaches a steady-state average velocity $v$.
This velocity and the corresponding friction coefficient of the probe
$\zeta=F_{ex}/v$ are obtained within a schematic model of mode-coupling theory
and compared to results from event-driven simulations. For small and moderate
drag forces, the model describes the simulation results successfully for both
the linear as well as the nonlinear region: The linear response regime
(constant friction) for small drag forces is followed by shear thinning
(decreasing friction) for moderate forces. For large forces, the model
demonstrates a subsequent increasing friction in qualitative agreement with the
data. The square-root increase of the friction with force found in [Fiege et
al., Granular Matter $\boldsymbol{14}$, 247 (2012)] is explained by a simple
kinetic theory.
