Writers, politicians, advertisers and graphic novelists all use rhetoric in the same way--to persuade you to do something, believe something, or buy something. To bring readers and/or viewers, around to their way of thinking.
Creators can rely on ethos (or authority) to get their message across. When the president gives a speech we listen - he is an authority. In the same way, advertisers often use celebrities to sell products. If I buy Kim Kardashian's makeup, I'll look as great as she does because she's an expert at looking good. There are also experts In The League of Extraordinary Gentlemen, where a "menagerie" has been brought together to save the British Empire--all because they have some ethos, as strange as it may be.
Often times you will see advertisements that offer proof that a product works, or statistics that report customer satisfaction. These are appeals to logic or logos. If studies show that 99 percent of people using XYZ toothpaste have whiter teeth, then it's only logical that you buy XYZ toothpaste because everybody wants whiter teeth.
Writers can also use pathos to convince viewers to do something, want something, or buy something. Those commercials that show poor, pathetic dogs and cats waiting at the shelter for a new home make viewers feel sorry for homeless pets--they want to adopt one, or better yet, they send money to those shelters. Consumers can also end up buying products because a television commercial shows what an exciting life you'll have if you buy that new car, plus you'll increase your popularity--and social standing. How about products that show happy, loving families sitting around the dinner table eating McDonald's, Swanson Fried Chicken, Ragu spaghetti, or Round Table pizza? These advertisers are all appealing to your emotions.
According to Stuart Hirschberg in "The Rhetoric of Advertising," consumers are often sucked in by "scenes emanating security and warmth, which the ad invited us to remember as if it were our own past." These kind of "ads thus supply us with false memories and invite us to insert ourselves into this imaginary past and to remember it as if it were our own." Creators of comic books do the same thing.
In the photo above members of The League are gathered around a dinner table. Remnants of the meal are visible and many of the members are having an after dinner smoke. Look at this "family" and think about how the creator is trying to get you--the reader--to insert yourself into this scene. How is your family like the League? Do you have an invisible cousin? A crazy uncle? A bossy aunt? A wanderlust second cousin, once removed? Are you trying to prepare a meal for vegetarians, vegans, and/or people that have a gluten-free diet? What do your family dinners look like and how does Alan Moore and Kevin O'Neill use ethos, logos, and especially pathos to invite you into their book?