Have you noticed how old people, especially couples, sit and stare at children in public with a longing, entranced gaze. There’s more to it than doting. It’s an unconscious desire for youth – not the youthfulness of young people in general, but the pure youthfulness of children.
What if when Death apears on the horizon, we unconsciously start seeking the elixir of youth – the special, magical energy of children. Perhaps the old people, with their spooky vampiric gaze, somehow actually steal it. (Maybe it’s more effective if there are two of them.) After all, children have energy to spare. It doesn’t do any harm. Perhaps it keeps the old vampires alive a bit longer.
Probably, some horrible Crowleyesque sacrificial energy-transfer ritual could confer immortality. But old people just do it without realising it.
Having reached old age, I’ve found myself starting to do it. I’d have to be careful, of course, make sure my wife (not old enough yet) is with me, and avoid inappropriate staring scenarios. I might get a few extra years!