  Highly eccentric orbits are one of the major surprises of exoplanets relative
to the Solar System and indicate rich and tumultuous dynamical histories. One
system of particular interest is Kepler-1656, which hosts a sub-Jovian planet
with an eccentricity of 0.8. Sufficiently eccentric orbits will shrink in
semi-major axis due to tidal dissipation of orbital energy during periastron
passage. Here our goal was to assess whether Kepler-1656b is currently
undergoing such high-eccentricity migration, and to further understand the
system's origins and architecture. We confirm a second planet in the system
with $M_{\rm c}= 0.40 \pm 0.09M_{\rm jup}$ and P$_{\rm c}= 1919\pm 27\,$days.
We simulated the dynamical evolution of planet b in the presence of planet c
and find a variety of possible outcomes for the system, such as tidal migration
and engulfment. The system is consistent with an in situ dynamical origin of
planet b followed by subsequent Eccentric Kozai Lidov (EKL) perturbations that
excite Kepler-1656b's eccentricity gently, i.e. without initiating tidal
migration. Thus, despite its high eccentricity, we find no evidence that planet
b is or has migrated through the high-eccentricity channel. Finally, we predict
the outer orbit to be mutually inclined in a nearly perpendicular configuration
with respect to the inner planet orbit based on the outcomes of our
simulations, and make observable predictions for the inner planet's spin-orbit
angle. Our methodology can be applied to other eccentric or tidally locked
planets to constrain their origins, orbital configurations and properties of a
potential companion.
