O/H and C/H (relative to the host star abundances) of the atmosphere of the planets simulated in the disc of WASP-84 (top) and CoRoT-9 (bottom) for varying initial positions of the planetary embryo in a disc of α = 1 × 10⁻⁴. We show the formation location that resulted in the simulated heavy element mass of the planet matching most closely with the observation (dashed red line), the constrained regions where the planet could have initially formed (shaded grey regions), and the H₂O and C evaporation fronts (dashed black lines).