Mass evolution of a 10 M_⊙ seeding black hole from z = 30 to z = 7, including Eddington accretion and relativistic SIDM Bondi inflow. Shown are four representative SIDM masses, m = 1,  10⁻¹, 10⁻², and 10⁻³ eV, evolved in a Press–Schechter median halo enhanced by an order of magnitude with a total SIDM supply fraction f_halo = 0.9. The heavier SIDM reaches the transition mass M_⋆ (at the corresponding redshift z_⋆, marked by crosses) earlier and experiences a rapid growth phase until saturating at the finite halo supply. These results demonstrate that the accretion process involves three stages: (i) a long early-time Eddington-dominated phase; (ii) a supply-limited Bondi-dominated phase starting around z = z_⋆ and ending at z = z_B after exhausting the SIDM of the inner-halo core, indicated by the sharp turns into a universal plateau; and (iii) a late-time Eddington-dominated phase, i.e., shown by the plateau.