Monsters in Fiction

What is a monster? Monsters are the personifications of things we fear and the unknown. They are not people. They are not intended to be or represent people. Monsters are placed into stories that try to describe things that go bump in the night and to evoke some macabre thrill, fear, or disgust in the audience. Monsters are dangerous and opposed to mankind. Either they're malevolent or simply indifferent to our suffering. They are characterized by extreme vices, strange powers, and mysterious weaknesses. They are meant as obstacles for the brave or wise to overcome, avoid, or flee from. Sometimes, the innate inhumanity they represent reinforces our humanity.

In the context of literature, a foil is a type of character who is used to contrast another character, and the effect of using a foil is to emphasize specific characteristics of one or the other character. Simply put, a good character's goodness is emphasized when compared to a bad character's badness. Monsters are the foil of humanity, and so it is inappropriate to humanize them. To humanize the monster is to make it into a new variety of a human with a variation on human morality and human thinking and human feeling. It suggests that on some level, every thinking thing is similar or the same. To do this is reductive to the purpose of monsters. Humanizing monsters takes away from their potential for mysteriousness and alienness, and it minimizes the horror of the unknown that they represent. The audience is meant to hear the pitter patter of its nails in the dark or its grim laugh, and to see the signs it left behind, not to learn about its complex social order and psychology. For some audiences or gamers, this is the premise of monsters that we desire. If you want to treat monsters as people, you ruin this premise of monsters for the rest of us, and you are a spoil sport. 

Were I to write my own TTRPG with a monster book, this is the text that would precede the rest of the book. I would elaborate with this. The lore of a monster is what is known about it, or thought to be known, by people in the setting. Lore is therefore incomplete and not guaranteed to be true. The Game Master or GM, being the curator of their game and setting, may change lore to suit it. The characters in the setting may be assumed to have no knowledge of the lore, and so they have to consult with experts. The characters must seek out and arm themselves with knowledge in preparation for their confrontation with danger. Lore is therefore earned by a process of discovery, and may require significant effort or cost or sacrifice. The stat block is a way of mechanizing the monster for play. Monster stat blocks remove the abstraction and mystery, and so they are metaknowledge, and not to be used as knowledge known by any ordinary character. In general, it is not within the spirit of the game to play your character using knowledge that you have that your character doesn't have, and is in effect cheating or spoiling the game as one might spoil the ending of a film for yourself or others. Players fear what they don't know. If fear and discovery would enhance a portion of your game, then the GM is encouraged to create their own monsters and to never use monsters as they are purely presented in the rules.

The reason why I would write a monster book for a TTRPG is so that I could write it with my desired premise built in. When you play a TTRPG such as D&D 5e for instance, it's fair to say that you can modify it however you want, but it's also fair to say that people have expectations for individual games, and when they're invited to play 5e, their expectation is to play with the 5e material as it is presented, and so they might be averse to any changes. The introduction to my monster book would be intended to prime my readers for my concept of monsters rather than theirs. If they agree to play their game using my monster book, they are agreeing to my premise, not theirs. I would explicitly address that my conception of monsters might be incompatible yours. If you try to seduce the dragon, it will automatically fail and for that turn, you will be vulnerable to dragon meaning you don't benefit from your armor or saving throws.