Posterior distributions of the interior structure of TOI-1453 c, showing mass fractions of the inner core, mantle, and envelope, as well as the water fraction in the envelope. The top row corresponds to a water prior compatible with a formation scenario beyond the ice line, while the bottom row assumes a water-poor composition, in agreement with formation inside the ice line. Colours represent three priors for the planetary Si/Mg/Fe ratios: stellar (purple, A1 and B1), iron-enriched (pink, A2 and B2), and uniformly sampled from a simplex (blue, A3 and B3). Dashed lines mark the median of each distribution, with priors indicated by dotted lines.