Oh, we can't do much. Not overtly, anyway. And certainly not when anyone (or anything) is watching.
But we are not without power. We are not without recourse or influence in the world.
In fact, you've probably enjoyed a personal experience with the dead in the course of your lifetime. Don't be surprised. Most people have. Where I come (came) from, we called it good luck, or more often, bad.
Now that I'm here, I know all about it. Or at least I'm learning all about it. It's fascinating, really, in a morbid sort of way. Fun? No. Exciting? No. Entertaining? Never. But fascinating? Yes, I would definitely have to say being dead can be fascinating.
What's fascinating about it? Well, as I said before, it's not a form of existence, really. Not an act of being. Death, the afterlife, is a sort of presence. It's hard to describe in temporal terms, but I'm sure you'll bear with me a sentence or two while I fumble for the proper words. Imagine a fog on a water, early in the morning. Imagine that you observe the sunrise and watch, minute by minute, as the roiling whiteness is dissolved in the growing heat. Imagine that precise moment when the last wisps seem to disappear or be flushed away, leaving only bright sunshine and a seemingly clear summer day. But imagine that you look up at the sun, which seems perfectly revealed at first, only to notice a kind of haze, a kind of halo of presence that lingers in the light long past the last visible traces of its sires. Well, that's how I feel. I am a fog dispersed, seen only before the brightest, most piercing of lights. A thinned presence of . . . character . . . of personality, I suppose. It's the closest I can come. I mean, after all, I'm still me. I have all my old worldly memories and thoughts and pathologies and perversions. Nothing has changed about my self in the slightest, that I can tell. Either for good or ill. Only . . . only there seems to be so much more of me. I feel so much larger, and smaller, than I ever was in life.