At least, I bet that you can't imagine them peeing. Think of it: Obi Wan Kenobi standing over a dirty toilet in Mos Eisley or hurrying around a big boulder to keep those little glowing-eyed dudes in the cloaks from whisper-croaking-spitting their amusement.
Jedi don't poo either. Try to imagine Windu Filteredbeer—or whatever Samuel L. Jackson's Jedi character's name was—say, "Damn, man, I need to take a righteous dump! The Force be with my bloated colon! It's losing structural integrity!"
Imagine Palpatine—Darth Sidious—biting his nails or popping a zit. Does he wear regular underwear, or are there some special and particularly evil briefs he puts on each morning when he gets up? They'd be black (of course), but would they be made of cozy, comfortable cotton? Do Sith Lords like cozy, comfortable cotton skivvies? Does he ever sit on his throne and squirm on it, thinking, Infernal hemorrhoids! Does he ever get jock itch? Does he examine the evil hairs in his evil ears and try to cut them with an evil pair of scissors?
Does Darth Vader ever take a breath (koooooooo-keeeeeeeeeee!) and say, frustrated, "Now my indigestion is com-plete ... buuuuuuuuuuuuuuuurrrrrp!"
One of the great weaknesses of fantasy heroes and villains is that their authors do almost everything they can to remove their humanity from them in order to make them appear unreachable and invincible. Even JK Rowling did this with Lord Voldemort. You didn't see him cutting farts just after coalescing back to his nasty, pasty little snaky body after Wormtail cut his own hand off into the cauldron and dropped in a dirty bone from Tommy's dad's grave and dripped in a bit of Harry's fresh young blood. If nothing else gives you gas, I don't know what will. A more accurate portrayal of his re-introduction into the world would have featured him walking amid his Death Eaters and saying: "Welcome!"--fffffft! "It's been thirteen—" bubblezzzzzoooofffffffgurgle!—"years!" "Harry! There you are, standing on the bones of myfffffffffffffffffffffffffftzzz-ather!"
Heroes also get the same treatment, as I just mentioned. What would happen if the Incredible Hulk suddenly developed an erection while tearing down yet another skyscraper? His pants seems infinitely stretchable no matter if he's Bruce Banner or his fearsome alter-ego, but can they accommodate that? If you're Iron Man and have a sudden bout of diarrhea while burning through the atmosphere, do you need to land in some forest somewhere and hurriedly strip off all that high-tech fighting armor, or has Tony Stark engineered a solution to such a potential problem? If so, has he accounted for the extra thrust generated once he releases his pent-up bowels? Genius, after all, can carry you only so far. Past that, one must rely on one's humanity and hope that anything dripping down your leg won't cause all that electricity humming around you to short circuit.
Too often fictional heroes have their humanity utterly excised. They aren't human; and for many, perhaps most, that is a plus, not a minus. What a shame. And how telling. We hold our physical beings in great contempt, and it shows in these stories. It isn't a coincidence that the Jedi don't pee or poo. It isn't a matter of "budgetary constraints" among producers and directors that we don't see Voldemort shedding a tear or Vader struggling to pull chopsticks out of his facemask after taking an unwieldy bite of alien sushi. Epic fictional heroes and villains aren't human—and yet, at least for the heroes, we are encouraged to be just like them. We are encouraged not to be human.
has to poo. That makes him a wimp. It makes him weak. Peter Parker is left
smashing cockroaches in his dank apartment, and so he's deserving of
condescension and contempt. It's only their heroic alter egos that are
celebrated and looked up to.
With one notable exception—Necrolius Anaxagorius—my heroes and villains all pee and poo. Even the vile Prince Trajan and his hated cohort Lord Pios pee and poo. Conor Kieran, Melody, Yaeko, Maggie, Luis ... these great heroes are human beings, and so I have proudly retained their humanity. Calliel Hiccum is an angel, and so is Ray Wilms. Both still have to pee and poo.
And Necrolius? He doesn't have to do either by virtue of his unbeingness. But let's be clear: it doesn't make him greater than those he consumes and enslaves; it makes him infinitely less. Perhaps, in the end, that’s the point.