Authors like to use themes to create a sense of unity or cohesiveness within their work. Some extend themes to the names of the characters, often beyond the similarities that would be expected for characters from the same culture or who all speak the same language. When the author does this, you have Theme Naming, for instance, all the female characters will have names of flowers or plants; all the names start with the same letter or syllable, groups of characters are named after groups of gods, demigods, or mythical heroes. As the list of subtropes demonstrates, there are a lot of possible themes (and that's not all of them, either)