There were maybe about 1,500 of the Old Ones left on earth. And maybe 3,000 or so thralls. And when the food supply began to be decimated by the legions of the dead, the Old ones became understandably worried. They could eat and survive on one thing, and the undead were depriving them of it. By the billions. What had been as simple as ordering out for pizza, now became as difficult as finding the rare restaurant that served truffles found in only one acre of Belgian woods.
Something had to be done, something they had never done before....
They broke up into battalions, companies, squads, and went all over the earth, looking for survivors. And saving them. Murasama blades whickered and snickered, and the dead fell like wheat before a scythe.
Gunships went up and down city streets, mini-guns and rockets cutting the dead down like a grinder, and humans, the few that were left, cheered from the rooftops. And their 'rescuers' did not need night vision devices.
They parked on rooftops, and were greeted as heroes. Their 'heroes' could smell whether or not a man or a woman had been spayed or neutered, rendered useless for their purposes. Such were seized and fed and bled and fed again, and nurtured as you would a milk cow.
Those who had their reproductive organs intact were carefully transported to safe places in the upper Midwest, provided with female companionship, and every luxury they could want, considering the dead world. And protection they couldn't see, from thralls that fed on deer, elk, and whatever else crossed their path. The dead didn't appear often, but when they did, silenced sniper rifles shattered their brains.
The Old Ones needed a new crop...