Orbital structure of accreted populations. Left: Mean eccentricity of merger remnants stars as a function of accretion time for all the mergers in the M31/MW HESTIA galaxies. The different symbols correspond to different simulations and galaxies and they are colour-coded by the stellar mass at the time of the merger. Right: Stellar-mass weighted distributions of the eccentricities for individual merger remnants (grey) and the mean distribution (red) at z = 0. Here, the eccentricity is multiplied by the sign of the angular momentum. Although the stars in the merger debris show a wide range of eccentricities, the mean eccentricity of the debris tends to decrease with time, whereas more recently accreted debris have slightly lower eccentricity. This evidently correlates with the stellar mass of the accreted system, which tends to be higher for the galaxies that accreted earlier, and thus evolved longer.