Grimm is an outright villain who despises all things that are traditionally seen as cute or nice, to the point of wishing to obliterate them from existence - which he seems to be able to do with his mere presence, which warps not only the world around himself but people and animals, making everywhere Grimm goes become a kind of Hell on Earth. He also expresses a bitter and sardonic attitude towards the worlds and their inhabitants. However, he is shown to be weakened by water or any other kind of fluid (including vomit) which will cause him to drown.