'Psionic control over probability.' What does this tell us? Not a whole lot. Especially taking into considering that this is based solely on observed data. And there's not a whole hell of a lot of that, either. At the most basic of levels, Domino is simply phenomenally lucky. This predilection things to go in her favor and against that of whoever's unfortunate enough to be facing her is usually subtle, even in a media where subtly is rather hard to attain. To date, her powers have manifested mostly in very simple ways--things falling on opponents, things not falling on her and those immediately surrounding her, or the convenience of a swimming pool situated just below a rout of escape. the examples are good, but what does all of this mean, exactly. What can and can't she do? Questions like this get posed to me a lot by people researching for fan fiction, and I've had to face the embarrassing truth that I don't really know any more than they do. I do however, have two theories to pose here. The first is my conjecture, and the second was posed to me by a good friend.
When working with a total unknown, it's best to try and narrow down the thousands of possibilities exist. The quickest way of doing this is to look for a like example. In the Marvel universe, 'luck' is not a unique ability, though it is comparatively rare. One of the flashiest examples comes in the form of Wanda Maximoff, the Scarlet Witch. Wanda's hex powers are, at their source, psionic probability altering abilities, and that's a phrase that should be familiar by now. The difference here is that Wanda's powers are both consciously controlled, and seemingly more powerful than Domino's. They're also enhanced by Wanda's skills with magic, but we're not going to get into that here. The point to all of this is that, in The Science of the X-Men, there's a nice section on Wanda, which takes a lot of guess-work out of it. Skipping over all the Newtonian theory and Schrödinger's damned cat, the gist of the entry is that Wanda is, essentially (at least in theory), altering reality, albeit on a small scale. Which is probably good, because aside from the notable exception of Franklin Richards, the high class reality wrappers have a tendency to go insane in big and messy ways. That is, she is altering circumstances on a very fine level, causing what could happen to happen. She doesn't create the impossible, she merely alters the world around her in such a way that the most beneficial of occurrences happens. The interesting result of this is that while these powers alter probability, they're also affected by it. There is a certain chance that their powers will fail to affect probability at all, a certain percentage of the time.
The heart of probability is this: there are, for any given situation there is a certain number of outcomes. This number can be big or small depending on the situation. A coin toss is a classic example--you have only two likely outcomes--the coin will be heads or tails. While other outcomes do exist, such as the coin landing on edge, or an alien invasion destroying the planet before the coin can land, the likelihood of such a thing happening is usually so small as to be ignored. In the framework of our theory, probability is being effected on a physical level. Something is enabling Domino and the Scarlet Witch to cause one outcome to occur over another, often upsetting the 'normal' outcome. This makes sense when considering things like rocks falling on the heads of opponents, of course, as it's not much of a stretch to imagine the slight 'nudge' it would take the rock to fall, rather than stay where it is. This theory also seems supported by the fact that neither can cause things that have no chance of happening to occur, such as their enemies suddenly becoming rabbits. This seeming limitation to the rules of probability may well be a function of the power level they operate on, since the above mentioned feat would not be impossible to someone with true reality warping capabilities.
Got a headache yet? Good. Get ready for a bigger one.
Told you it was going to get bigger. Okay, this theory is not mine in origin. It was proposed by a friend, and I just couldn't find a flaw in it. After all, precognition is a psionic power as well. This theory is interesting when you start looking at examples of what Domino has done. The aforementioned rock falling and several of the explosions can be explained by reality warping on a very minute level. But how, exactly, do you explain the amazing good fortune of taking a chance dive out of a window, only to find a swimming pool below to graciously break her fall? After all, a swimming pool is not something easily affected by a 'nudge' in reality. The swimming pool was either there, or it wasn't. We can assume that given its nature, it was being observed by someone, and thus not subject to the same fate as Schrödinger's poor cat. This could also be written off as a fluke of the writing and thus an unworthy example, but since none of this is real anyway we're going to just assume that this was, in fact, a valid example of Domino's abilities at work. So, in this case, a nudge of reality doesn't seem a likely case, unless Domino's powers are working well in front of when they're expressly needed, which wouldn't seem likely in the case of reality altering. We can assume that she did not nudge the swimming pool into existence. How then, do we account for this occurrence? Precognition.
In this case, we are talking about precognition on an amazingly limited scale. Domino would have no conscious awareness of what it was she was perceiving, nor could she tell you anything about it. Instead, if this were the case, she would be 'seeing' the future on a limited and unconscious level, just enough to drive her towards certain actions. This theory is, of course, blown out of the water if you don't believe individual actions can affect the path of time, even in a limited scope, so we're going to go ahead and assume it can. So then, back to that swimming pool. In this case, there is no issue of trying to nudge a rather large body of water into existence. There is simply the choice to dive out the window or not to. We're back to really simple things to understand. Kind of. See, realities, theoretically, also operate on probability. Here we have to assume almost unlimited possibilities, of course. Some, however, are much more common than others will be. Whatever the case, all Domino has to do here is 'see' whether or not a dive out the window is going to turn her to pavement pizza or not. It's seeing the future--just a very short time into the future. Using this knowledge (unconsciously, of course) she leaps out the window, know that the pool will be there. She just doesn't know that she knows.
That's two takes on just how Domino does what she does. There are other interesting points to ponder, such as what the true level of her control is--the one documented time she attempted to use her powers consciously, she got the desired results, but not in the way she intended. The quick and dirty version of the incident (see Cable #38 for details) is that she tried to work the weapons system on an unfamiliar ship, in a desperate bid to keep herself, Cable, and Kane from being blown up. The weapons did fire--not because she got them to work, but because the owners of said ship happened to show up just in the nick of time. It's really a cool subtle little example that takes a rereading or two to catch. The question becomes--did she actually consciously trigger her powers, but lacked the ability to control them--or did they just fire on automatic as has previously been the case?
A second fun fact to mull over is what, exactly, her true power level is. One would assume that for someone without even conscious access to their abilities, no mater how powerful they may be, the result is going to be modest, at best. Domino has had no training what-so-ever, nor has she ever shown any inclination to learn more about her abilities. Who knows what kind of power might be lying latent, waiting to be tapped?