Softness and polarizability are calculated for different complexions of two-state ensembles of various helium isoelectronic systems (He, Li+, Be2+, B3+, C4+). It is shown for the first time for the systems studied that an increase in the excited-state contribution in a two-state ensemble makes the system softer and more polarizable, as expected from the principles of maximum hardness and minimum polarizability.