Explanation[edit]
Especially well known are three of his major characters Black Hat, White Hat and Beret Guy. These three characters do not often appear together in the same comic, except in large comics where they can appear without interacting.
They have all three appeared in the large drawing comics 1000: 1000 Comics, 1110: Click and Drag and 1608: Hoverboard and also in the interactive comic 826: Guest Week: Zach Weiner (SMBC), and in 1756: I'm With Her and on the cake in 1581: Birthday. But in those instances they do not interact. All three characters appear in the same place at once in 2348: Boat Puzzle; however, they still do not speak to one another, as all of them direct their speech towards the ferryman Cueball.
Black Hat and White Hat have only ever spoken together in four comics: 1708: Dehydration, 1881: Drone Training, 2174: First News Memory, and 2348: Boat Puzzle, yet they only speak directly to each other in the second comic; in the other three, they only speak in the same setting.
Similarly, Beret Guy has also only twice spoken to White Hat in 291: Dignified and 1772: Startup Opportunity. White Hat replies in the title text of the former comic, but White Hat has never spoken directly to Beret Guy in the main comic. However, the same can't be said for the latter.
Beret Guy has though been in at least six other comics together with Black Hat and two others with White Hat. He has, however, never interacted directly with Black Hat!
White Hat and Beret Guy also appeared in 1028: Communication, where they showed two different examples of communication, and thus did not appear together, and similar in 1645: Toasts where there is no reason to believe that they toast at the same party.
Black Hat and Beret Guy appear together in both 785: Open Mic Night and 804: Pumpkin Carving but in both comics they talk to other people and not to or with each other. The open mic stage is probably the same, but they are not on it at the same time, and the pumpkin carving could be done in different locations. In 434: xkcd Goes to the Airport and 442: xkcd Loves the Discovery Channel they appear in different panels showing situations taken out of context with each other and finally there are two special comics where both appear; 1037: Umwelt, where they appeared in two different versions of the comic, not visible from the same location; and 1663: Garden where both characters can grow out of the ground, but of course they do not interact here either.
