We Are All Either Dolls Or Seeds

A serum has been made that stops death. Nearly everyone has taken it, but there are those who remember their past lives and that death cleanses the soul. They choose to live forever in that way. The undying are content to leave them alone until souls stop being recycled. Now all they want are human children, not the empty shells they're giving birth to. Through meditation and astral projection, the main character sees the dolls are not so empty after all.