It is known that methanol and ethylene form distinct one-dimensional patterns along the dimer row on the Ge(100)-2 × 1 surface. A unified explanation for the pattern formation is attempted in this study through theoretical methods. Kinetic parameters of the precursor-mediated adsorption of the two molecules are calculated using density functional theory methods. The potential energy surface along the reaction channel was found to vary according to nearest-neighbor occupation. Monte Carlo simulations were performed with calculated kinetic coefficients and assumptions of a one-dimensional lattice with nearest neighbor interactions. The simulation results effectively reproduce the coverage-dependent evolution of longer-range adsorption patterns.