Isa's world is a world of magic, and one that is at war. To be more specific, the world is at war with the Demons, or as they call themselves: 'the Endarkened'. It's not the first time it's happened either - there was a great war earlier, so far back that only the elves remember it. The Endarkened lost that time, and they aren't too pleased about it. They have long memories, you see, and it's quite possible that they were merely biding their time and waiting for the next opportune moment.
Isa himself, however, is unaware of this. He knows only the things he's seen: that his hometown was all but destroyed in a single night by creatures of the Dark, and that things don't seem to be getting better anytime soon. Given that he only managed to survive the events that destroyed his town by being lucky and hiding you can't exactly blame him. The fact that he then spent several months ekeing out an odd sort of life in the wilderness didn't exactly help matters any, although it certainly made him good at killing things.
It did not, however, do anything for his sense of trust or for his tendency to be quiet when he has nothing to stay. The latter became useful during his time in the wilderness, the former may never come back quite the same way although his stay in the dressing room has at least been getting him used to the concept of people again. It's a strange place to him, but he's getting to the general concept of it, if nothing else.