Example behavior of multi-planet system, with π Men c (black solid) at its present-day semi-major axis, two other planets of the same mass located at 0.103 au (red dotted) and 0.185 au (blue dashed), and π Men b. Perturbations from planet b lead to modest eccentricities (top panel) and mutual inclinations among the planets (bottom panel; i.e., each planet has a slightly different mutual inclination with planet b). Dynamical evolution computed in mercury6. Chambers (1999), modified to include general relativistic precession of all planets.