Even though my focus right now is on pure fantasy, your work is so evocative that it makes me want to read through all the Locastus subs.
There are so many ways the mayhem these critters cause could bring about difficulties and misunderstandings, that they are sure-fire conduits to adventure.
I have a soft spot for techromancy, and this could have great applications in a steampunk game. "Oh no, we need this device to run and save the town! But it's infested with cog devils!" I don't know why I think of these little things as adorable, but I do. While they don't really need an origin story it would be nice if there were some theories.
"He who speaks with his fists" Love it. Great character. Person of depth who has no speaking lines. Awesome littel enigma without a real answer. Great job painting and picture and I love the quotes scattered. Really put it all together and gave me enough to want to stay the hell away from him. Too bad PCs will have to learn the hard way!