

Given that the sun is a fiery ball of energy and the moon is responsible for the tides, this trope can also lend itself to Fire/Water Juxtaposition. Light/Darkness Juxtaposition can apply when the moon is associated with darkness and the sun with light. Compare Red Oni, Blue Oni and Elemental Powers. The contrast between the two is a common Cosmic Motif (and color motif, particularly yellow and purple, if not outright black and white). The moon does give light in the darkness, and just because it's less constant and more mysterious doesn't make it bad. Can also go in line with Light Is Not Good, although it can go with Dark Is Not Evil when dealing with characters like Friendly Neighborhood Vampires.

Lycanthropes, the most famous example, are depicted as having their transformations trigger when the moon is full. On the other end of the spectrum, the moon also has connotations of light, but it's been associated with The Undead and other supernatural creatures. This can get even worse with monsters and antagonists that are either made of those elements and/or are able to utilize them without any ill-effect to their being.

If associated with malevolence, can go in line with Light Is Not Good-imagine sunburns, imagine merciless UV rays scorching everything they touch. Undead or demonic creatures have been depicted as being vulnerable to it, likely to its associations with light and fire. Due to its nature as an object that provides warmth and light, the sun has played symbolic and important roles throughout the history of fiction.
