It occurs to me that the background should be similar to that in contemporary political thrillers like Louise Penny and Hillary Clinton's State of Terror. And the super people should be like those of Evelyn York in "New Orders" -- produced by a secret enhancement project. Only that project should be the work of a group of wealthy yet idealistic people afraid of how the world is going with constant wars instigated by dictators and political/religious extremists of all kinds. They can't hide from the heroic enhancees, but some of them go on the warpath anyone and the supermen and superwomen will take action. Also, no kryptonite or the like -- they don't want to take any chances in love OR war.