Two typical examples of the Styx orbital evolution resulting in either instability (left panel) or the final configuration, which is significantly different from its current orbit (right panel). Left panel: initial conditions used are a_C ∕R_P= 5, e_C = 0.001, Ω_C ∕n_C = 2, A = 10, and Δt_P = 600 s. Styx is ultimately ejected from the system when the system crosses the 4/1 MMR between Charon and Styx (not shown), resulting in a strong increase in Styx’s eccentricity. Right panel: initial conditions used are a_C ∕R_P= 4, e_C = 0.001, Ω_C ∕n_C = 2, A = 10, and Δt_P = 6 s. The orbital eccentricity is excited, due to the crossing of the 4/1 and 7/2 MMRs (not shown), to attain the mean value ≃ 0.1, which is substantially larger than the current Styx eccentricity.