  Drastic changes in protoplanets' orbits could occur in the early stages of
planetary systems through interactions with other planets and their surrounding
protoplanetary or debris discs. The resulting planetary system could exhibit
orbits with moderate to high eccentricities and/or inclinations, causing
planets to perturb one another as well as the disc significantly. The present
work studies the evolution of systems composed of an initially inclined planet
and a debris disc. We perform N-body simulations of a narrow, self-gravitating
debris disc and a single interior Neptune-like planet. We simulate systems with
various initial planetary inclinations, from coplanar to polar configurations
considering different separations between the planet and the disc. We find that
except when the planet is initially on a polar orbit, the planet-disc system
tends to reach a quasi-coplanar configuration with low vertical dispersion in
the disc. When present, the Zeipel--Kozai--Lidov oscillations induced by the
disc pump the planet's eccentricity and, in turn, affect the disc structure. We
also find that the resulting disc morphology in most of the simulations looks
very similar in both radial and vertical directions once the simulations are
converged. This contrasts strongly with massless disc simulations, where
vertical disc dispersion is set by the initial disc-planet inclination and can
be high for initially highly inclined planets. The results suggest caution in
interpreting an unseen planet's dynamical history based only on the disc's
appearance.
