  We develop a simple toy model for polarized images of synchrotron emission
from an equatorial source around a Kerr black hole by using a semi-analytic
solution of the null geodesic equation and conservation of the Penrose-Walker
constant. Our model is an extension of Narayan et al. (2021), which presented
results for a Schwarzschild black hole, including a fully analytic
approximation. Our model includes an arbitrary observer inclination, black hole
spin, local boost, and local magnetic field configuration. We study the
geometric effects of black hole spin on photon parallel transport and isolate
these effects from the complicated combination of relativistic, gravitational,
and electromagnetic processes in the emission region. We find an analytic
approximation, consistent with previous work, for the subleading geometric
effect of spin on observed face-on polarization rotation in the direct image:
$\Delta {\rm EVPA} \sim -2a/r_{\rm s}^2$, where $a$ is the black hole spin and
$r_{\rm s}$ is the emission radius. We further show that spin introduces an
order unity effect on face-on subimages: $\Delta {\rm EVPA} \sim \pm
a/\sqrt{27}$. We also use our toy model to analyze polarization "loops"
observed during flares of orbiting hotspots. Our model provides insight into
polarimetric simulations and observations of black holes such as those made by
the EHT and GRAVITY.
