Surface density plot of initial condition A.1 reconstructed from ROMULUS25 system A. The top panel shows the distribution of the dark matter component, the middle panel the stars, and at the bottom the gas. The heaviest black hole BH1 is represented by the black dot, BH2 by the triangle, and BH3 by the square. Galaxy 3 did not contain any gas, therefore, no overdensity around BH3 is present in the bottom plot.