Evolution of the primary stars for our models with q_i = 0.95 in the HRD (left) and sHRD (right). The markers indicate the position where the primaries reach core collapse, and the color-coding is as in Fig. 2. Thick gray lines reflect the ZAMS and terminal-age main-sequence (TAMS) positions of single stars, and thin gray dashed lines show the main-sequence evolution of single stars with initial mass displayed at the edges of the tracks. For models that leave the RSG regime after core helium ignition, dots are placed on their tracks at a fixed time interval of 50 kyr.