Variable Star by Robert A HeinLein & Spider Robinson

self-defense courses. I know how to fall properly, and do so as a matter of reflex in normal conditions. But not in a one-gee field. I went down hard on my back, and all my air left me in a single explosive syllable, and only the extreme thickness of the carpet kept me from cracking my skull. I remember feeling quite unhappy for a moment, there. Then the eighteen-kilo mass landed on my groin, and I felt much worse.
    Sometime later I forced my eyes open. Closed them quickly. Reopened them cautiously. Half a meter from my nose, a little girl—
    “Why don’t you look where you’re going?” she asked.
    Make a mental note, Joel: next time you tell an AI you want quiet and it keeps talking— listen . “Because I’m a dolt.”
    “Oh.” She thought about that. “I’m a Conrad.”
    I looked her over. She appeared to be somewhere around seven Terran years old. And adorable. “Are you all right?”
    She frowned, and stuck her chin out slightly. “Yes, I am. Daddy says I don’t have bones.” She moved her gaze away. “But I think my skyboard’s broke.”
    The object named lay beside us. It looked like a conventional skateboard—minus the usual wheels, motor housing, onboard computer, and data port. Like a miniature surfboard, in other words. I had no doubt that it could fly—when it wasn’t broken—because it had been at head height when I’d first encountered it. But I could not guess how.
    “I’m sorry.” I’d have to replace it. There went my scholarship, probably. “Uh, what’s your name?”
    “I’m Evelyn.”
    “Hello, Evelyn. That was my mother’s name, too. I’m—”
    “You’re Joel, of course. I’m not a baby .”
    “Certainly not! Not by a good ten kilos.”
    She giggled—then frowned. “Am I hurting you?”
    “Only when I breathe.”
    She was off me and up on her feet at once. “Jinny is my favorite cousin. I think she’s rickety all through. Don’t you?”
    “Yes. I think I do, anyway.” I sat up. When that didn’t kill me, I got to my feet and examined my costume for damage.
    “Are you going to marry her?”
    I opened my mouth and closed it again, twice. “We’re still discussing that,” I managed finally.
    “Do you love her?”
    “Evelyn, I’m afraid we’ll have to finish this conversation another time. I’m late for an appointment with your—” What would the relationship be? “For a very important appointment. Please excuse me.”
    She grinned. “Never mind. I saw you blush.”
    I did it some more. This was Jinny’s cousin, all right. “I really mustn’t be late.”
    She waved a hand majestically. “Don’t matter about it. Just tell Grandfather Rich I made you late.”
    I realized my flashing-firefly guide was beginning to move off down the corridor: hinting. “It was wonderful to meet you,” I said hastily “Sorry I broke your board. I’ll get a new one to you as soon as I can.”
    She giggled. “You’re silly.”
    I followed her pointing finger. A new skyboard was just arriving, gliding along the corridor at knee height. It was as featureless as the other, not so much as an antenna showing. Suddenly I saw that the firefly had nearly reached a corner. In another few seconds it would be around the bend. “Great. I’ll see you around.”
    “It’s okay, Joel. Gran’ther Rich will think you’re rickety-tickety. You’ll see.”
    I know a compliment when I hear one. I bowed—and did not quite sprint away. I found the firefly around the corner, waiting for me, but pulsing faster to indicate impatience. I breezed right past it at double time, made it scramble to catch up and pass me again, and felt the tiny satisfaction that comes to an idiot who has successfully insulted a piece of software. I slowed to walking pace—and it kept on going at double time. I ended up reaching my destination slightly out of breath, and not quite dripping sweat.
    I planned to pause outside the door for at least two or three deep breaths. But the infernal thing opened as