Alex had no clue at all as to what his new found business partner really was. So he took his words at face value. While intelligent and a good actor, Alex wasn't fond of lying, and wasn't good at discerning lies. Besides, he didn't need to know. But as for his power, "I can manipulate gravity. Completely and totally. Of course, some things are harder than others, but many things are possible. I can change the direction gravity faces, the intensity of gravity, and many other things. It's taught me a lot. Here, look," He held up a ball of iron that was on the table and it began to float. Suddenly, various small objects began to rotate around it.
"I'm not actually influencing the other objects. Just the ball itself. Apparently, the sun works like this, and our entire world would be one of the various things around it. At first, I though our planet was in the middle. Then I immediately challenged that though. Why WOULD be be the center of everything? As I observed more, I discovered this as well..." Suddenly, around the other objects, he allowed more to orbit around those. And then he lifted another ball separate from it all, and more scraps of metal and stuff orbited it, with smaller things orbiting those as well.
"From my observations, This is how the universe works." He grinned at Deimos.