Because I thought: what if there is a fellow who exists only in one universe (through no doing of his own)? If you read, you'll see how dic was talking about the "Kingdom of God" being in all of us, and raised Catholic as I was, we're taught that god is in everyone. And I used to think of Hell not as fire and brimstone, but the absence of god. So, then, would Mr. One-Universe be the Antichrist, or the Messiah? In only one universe, he would appear to be without God to anyone sensitive to Dick's divine multidimensionality; sort of cut-off. But it's also possible that his existence could herald the One True Universe (aka the Kingdom/Heaven). Which is all hogwash, really, leaving the "god" stuff out of it; there's nothing in my knowledge saying that the universe has to collapse to a single waveform, nor do I any longer think the universe is a gigantic equation working itself out to a solution or equilibrium.
For a long time, I've been interested in the concept of a Schrödinger's box and heroes. I think I've written before about the definition of many greek gods and demigods not so much as immortal in the omnipotent/invincible sense but as "fated not to die" (most clearly demonstrated in the awesomely titled book five of the Iliad: "Diomedes Fights the Gods", which was to be a centerpiece of my Heavy Metal Rock Opera magnum opus titled simply "Ilium." Because if rage, betrayal, and stabbing gods with spears isn't good metal fodder, I don't know what is). Think of a hero not in terms of their actions but in terms of the outcome. A classic hero is one who, no matter the setbacks, eventually succeeds (even if the result is their own death, as with a tragic hero/Pyrrhic victory). And if you make the cheesy sci-fi standard assumption that every action creates two outcomes, you must then think of the hundreds, thousands, or millions of universes a hero creates where they also fail at any of the steps along the way. The reason they are the hero is that they are the instance of themselves who just so happens to follow the many-worlded path through to completion of their objective (and, of course, there are an infinite number of such universes, but they are a subset of the whole of infinity). So what if there was a hero who made use of a Schrödinger's box to find universes where they were always successful? To an extent, I suppose you could say that of my character Miguel d'Vainqueur, though his is not a deliberate choice. But could you make a career out of being a hero who does what's needed because you know, in some percentage of the universes that emerge from your action, that you are successful? No superpowers necessary; just faith in the popular interpretation of quantum mechanics. Because, if this wasn't clear from the wiki, when you enter a Schrödinger's box situation (which is to say, life or death, though most situations are not exactly 50/50 probability of survival), your waveform is split and collapses in some universes, persists in others. But due to the split, in the universe where you survive, you are not aware of the others where you didn't. Only those waveforms are. Some authors have used the box as a method of parallel universe travel, often for comedic effect. It's like the old transporter problem; would you willing walk into a device that you knew for certain would kill you, at least in some sense of the word?