Book: Twilight's pet

There are people-creatures, which, if you disappear, then all will be easier: children of drug addicts, not causing his parents to tears because they all cried; fathers-drunk, spouting at every opportunity and an awkward case of their children and causing a flinch at the sound of his own voice; mother-sadistic, which once upon a time was love, and now they suck other people's lives as vampires blood. And there are people-aphids. They will be gone, and... nothing. But unless the smell is bad, and then faded.