  In this article, we consider an interesting class of optical and other
systems in which the interaction or coupling makes the systems to be
$\cal{PT}$-symmetric. We aim to compare their dynamical behaviors with that of
the usual $\cal{PT}$ symmetric systems with intrinsic loss-gain terms. In
particular, we focus on the interesting non-reciprocal nature of the $\cal{PT}$
symmetric systems which has a promising application in optical diodes and
optical isolators. We check whether the non-reciprocal nature is common to all
$\cal{PT}$ symmetric systems and, if not, what are the situations under which
it can be observed. Due to the recent interest in studying spontaneous symmetry
breaking in coupled waveguide systems, we here present such symmetry breaking
bifurcations in certain reciprocal and non-reciprocal $\cal{PT}$ symmetric
systems.
