There's other work to do in Flatland. Hiro's good with avatars, so he writes himself an invisible avatar—just because, in the new and more dangerous Metaverse, it might come in handy. This is easy to do poorly and surprisingly tricky to do well. Almost anyone can write an avatar that doesn't look like anything, but it will lead to a lot of problems when it is used. Some Metaverse real estate—including The Black Sun—wants to know how big your avatar is so that it can figure out whether you are colliding with another avatar or some obstacle. If you give it an answer of zero—you make your avatar infinitely small—you will either crash that piece of real estate or else make it think that something is very wrong. You will be invisible, but everywhere you go in the Metaverse you will leave a swath of destruction and confusion a mile wide. In other places, invisible avatars are illegal. If your avatar is transparent and reflects no light whatsoever—the easiest kind to write—it will be recognized instantly as an illegal avatar and alarms will go off. It has to be written in such a way that other people can't see it, but the real estate software doesn't realize that it's invisible.