Relativistic (Eq. (39) red solid lines, and Eq. (43) blue dot-dashed lines) and classical (dashed lines) dynamical friction force as a function of the test particle velocity v_T for three different cases with isotropic relativistic distribution. Shown are a 10 M_⊙ BH in a star cluster with velocity dispersion σ ∼ 10 km s⁻¹ and core density of 10² M_⊙ pc⁻³ (left panel); a 10⁷ M_⊙ BH in a galactic core with σ ∼ 500 km s⁻¹ and density of 4 × 10⁶ M_⊙ pc⁻³ (mid panel); and a stellar mass BH in a relativistic dark matter cusp around a SMBH with σ ∼ 2 × 10⁴ km s⁻¹ and mean density of 7 × 10^t g cm⁻¹ (right panel). In all cases the relativstic and classical curves are normalized to the value of the main peak of the classical.