Mass ratio as a function of time for different accretion delays on the inner (purple lines) or the outer planet (green lines). The planets are located in the 2:1 period ratio configuration. The two panels represent two different viscosities: α = 10⁻³ in the left panel and α = 10⁻² in the right. Darker lines represent shorter delays. Note that this time the mass ratio is displayed on a logarithmic scale (previous plots are on a linear scale) due to the extreme mass ratios induced by our initial setup here. The dots mark the moment when both planets have reached at least 0.3 M_J and can be considered gas giant planets. The gray rectangle represents the region where the mass ratio lies between 0.25 and 0.5 and shows the region where Jupiter and Saturn meet the required conditions to enter common outward migration, for α ≲ 10⁻³ (Masset & Snellgrove 2001; Pierens et al. 2014). Independent of the viscosity, all the mass ratios quickly tend toward the m_out/m_in = 1 line, leading to similar planet masses in both cases (0.8 < m_out/m_in < 2 after 10⁵ yr).