For now, I can say that “skidders” are the unholy combination of both zombie and vampire. As you may know from the story (I don’t know how far along you are yet), inhibitors are often used to delay the inevitable progression of zombieism, most often from a type II stage to a type III stage. People can live for years on inhibitors and survive as a type II zombie. Now, vampirism is a natural zombieism inhibitor, but it carries with it the vampiric curse. So in very rare circumstances where no normal inhibitor is available, some people voluntarily (or not-so-voluntarily) are infected with vampirism to prevent further zombieism progression. It is considered a desperate last measure, and often a fate worse than death… a hugely damning and awful state to be afflicted with both types of infections.

As for “genelons,” I don’t want to give away too much, since they figure prominently in FETIDUS Book 2. But basically, they are trans-humans or post-humans. They are essentially highly modified beings with mostly human DNA that have undergone advanced genetic splicing. The various procedures for splicing are banned in most countries, with rare exceptions granted for “licensed genelons,” who have to disclose their full genetic history and undergo extensive tests. In some cases, the splice work is so good that there is no way you can tell someone is a genelon. For now, I’ll stop there.

Hope that answers your questions!