Evolution of the BH mass for all the tested BH seeds, grouped by ϵ_c. Different colours indicate the initial BH mass, whereas the line style denotes the BH spin: solid lines for a = 0.99 and dashed lines for a = 0. The x-axis is shown using a symmetric logarithmic scale with a linear threshold of 10⁻² to allow visibility near t = 0 while preserving a logarithmic behaviour at larger values.