In random-interaction ensembles, the electric quadrupole moments (Q) and magnetic moments ($$\mu$$ μ ) of the $$I^{\pi }=11/2^-$$ Iπ=11/2- isomers of the Cd isotopes predominantly exhibit a linear correlation with the neutron numbers, corresponding to the recently emphasized linear Q and $$\mu$$ μ systematics in realistic nuclear systems. Although the seniority scheme enhances such predominance (more essentially for $$\mu$$ μ ), the configuration mixing due to quadrupole-like and $$\delta$$ δ -force-like proton–neutron (pn) interactions is responsible for the linear Q and $$\mu$$ μ systematics, respectively, in realistic nuclear system, as well as random-interaction ensembles.