Cuno kinnieis it ever explained in vermintide why the ratmen are working with evil humans
It is Swiff@georgespolitzer Opportunism: the skaven faction was massively set back by the events of the first game, including the assassination of most of their leadership. They needed reinforcements, and still had tunnel/portal access to the heart of the empire, and so brokered an alliance with the rotblood tribe: They get access to the heart of the empire without having to march overland from the north, and the rats get warm bodies to execute their schemes
@swiff ooo thank you! I was wondering that a lot!
@georgespolitzer also there's just thematic crossover: the humans in question are specifically in service to the god of plagues, and the skaven have their own unique brand of disease magic, so there's likely just some inherent kinship there. The villains of Vermintide are literally using the Power of Friendship to fight a war