But you did recommend figuring out the fetish of your viewers. You can't have your cake and eat it too on this one. If you're drawing porn for fans of Undertale, MLP, Fortnite, or whatever the latest thing is that adult kids are buying these days, you're really always going for that lowest common denominator. Because it's a numbers game, it's always just going to be the usual thing. If you can draw more fetishy stuff, it's because there's so many people in the fandom that there's still a good market for the fetish within the massive population, not because the fetish is special to the population.
At the end of the day, your advice for getting popular with drawing porn is to draw popular porn, dude. It's technically true but it's also a bit tautological.