Creatures, especially minifigs, can embrace a diverse array of genre choices. Once, this was as simple as hat style. Now, however, the personification is somewhat more complex. Theme in the BrikVerse has always been a flexible concept. In olden times, minifigs that wanted to embrace a new theme would just swap hats and be done with it. Hats came with their own wealth of implied genre, character, and story. Minifigs didn't need to be bothered with it. While there are still some proponents of the old ways, many newer generations of minfigs have developed a fondness for Kanon and all its workings. Generic theme and genre serve mostly as stereotypical relativistic starting points for describing character, sweeping backgrounds that establish a minifig's general place in the universe. Some characters and Factions never evolve beyond this stage in narrative development...and that's okay because there will always be a need for burger flippers at the space-time spanning fast food chain BrikDonalds...where others either move on to create whole new Kanons for themselves or add rich nuances to existing ones.
The Castle, City, and Space themes are the most prevalent in the BrikVerse. These are very similar to their counterparts in other Legitimitium Universes, only gaining their special BrikWarsiness through interaction with with the various specifically themed locations, Storylines, and the whole host of twisted natives.