Lightning

the house," Chris said, "they're from the future, too."
    "I think so. They were planning to kill my guardian, you, and me. But we killed some of them instead and left two of them stranded in the Mercedes. So… what are they going to do next, kiddo? You're the resident expert on the weird. Do you have any ideas?"
    "Let me think."
    Moonlight gleamed dully on the dirty hood of the Jeep.
    The interior of the station wagon was growing cold; their breath issued in frosty plumes, and the windows were beginning to fog over. Laura switched on the engine, heater, defroster, but not the lights.
    Chris said, "Well, see, their mission failed, so they won't hang around. They'll go back to the future where they came from."
    "Those two guys in our car?"
    "Yeah. They probably already pushed the buttons on the belts of the guys you killed, sent the bodies back to the future, so there're no dead men at the house, no proof time travelers were ever there. Except maybe some blood. So when the last two or three guys got stuck in the ditch, they probably gave up and went home."
    "So they aren't back there any more? They wouldn't walk back to Big Bear maybe, steal a car, and try to find us?"
    "Nope. That would be too hard. I mean, they have an easier way to find us than to just drive around looking for us like regular bad guys would have to do."
    "What way?"
    The boy screwed up his face and squinted through the windshield at the snow and moon glow and darkness ahead. "See, Mom, as soon as they lost us, they'd push the buttons on their belts, go home to the future, and then make a
new
trip back to our time to set another trap for us. They knew we took this road. So what they probably did was make another trip back to our time, but earlier tonight, and, they set a trap at the other end of this road, and now they're waiting there for us. Yeah, that's where they are! I'll just bet that's where they are."
    "But why couldn't they come back even earlier tonight, earlier than they came the first time, back to the house, and attack us before my guardian ever showed up to warn us?"
    "Paradox," the boy said. "You know what that means?"
    The word seemed too complex for a boy his age, but she said, "Yes, I know what a paradox is. Anything that's self-contradictory but possibly true."
    "See, Mom, the neat thing is that time travel is full of all kinds of possible paradoxes. Things that couldn't be true, shouldn't be true—but then might be." Now he was talking in that excited voice with which he described scenes in his favorite fantastic films and comic books, but with more intensity than she had ever heard before, probably because this was not a story but reality even more amazing than fiction. "Like suppose you went back in time and married your own grandfather. See, then you'd be your own grandmother. If time travel was possible, maybe you could do that—but then how could you have ever been born if your
real
grandmother had never married your grandfather in the first place? Paradox! Or what if you went back in time and met up with your mom when she was a kid and accidentally killed her? Would you just cease to exist—
pop
!—like you'd never been born? But if you ceased to exist—then how could you have gone back in time in the first place? Paradox! Paradox!"
    Staring at him in the moon-painted darkness of the Jeep, Laura felt as though she was looking at a different boy from the one she had always known. Of course, she had been aware of his great fascination with space-age tales, which seemed to preoccupy most kids these days, regardless of age. But until now she hadn't gotten a deep look inside the mind shaped by those influences. Evidently the American children of the late twentieth century not only lived interior fantasy lives richer than those of children at any other time in history, but they seemed to have gotten from their fantasies something not provided by the elves and fairies and ghosts with which earlier generations of kids had entertained themselves: the ability to think about abstract concepts like space and time in a manner far beyond their intellectual and emotional age. She had the peculiar feeling that she was speaking to a little boy and a rocket scientist coexisting in one body.
    Disconcerted, she said, "So… when these men failed to kill us on their first trip tonight, why wouldn't they make a second trip
earlier
than the first, to kill us before my guardian warned us that they were coming?"
    "See, your guardian already