In the shandite type solid solution InxSn2–xCo3S2 the transition from half metal ferromagnetic Sn2Co3S2 to the new thermoelectric InSnCo3S2 is related to A = In, Sn on different crystallographic sites. Effects and origin of crystal and electronic structure changes induced by A = In are now investigated within the solid solution 0 ≤ x ≤ 2 including In2Co3S2. Effects are studied from X-ray data, 119Sn Mößbauer spectroscopy, and ab initio calculations. Their origin is explored by DFT modeling on site preference of In and Sn in a supercell, electric field gradients (EFG), spin polarization, band structures, and direct space analyses (ELF, AIM). Indium is found to cause the crystal structure distortion on one A site, the electronic structure distortion to the other, as a consequence of inverted anisotropic bonding.