Short Stories with Tragic Endings

I am on the edge of a forest and there are a few of my friends around me. There is guy a with
bright red hair that somewhat resembles a joker or an elf or something standing up front. He is
supposed to be Hagrid I think. He shows us this furry little rat. I forget what it did but somehow
it multiplied and you could make an army out of them. I was thinking about army rats when
the dream ended.