A Troubles Paradise

It all started way back before I was born, we had a new queen and with that, new rules. Nobody knew what to expect apart from maybe new curfews or new guards outside the city. Nobody knew what was coming. There's us, the Free walkers, and then there's the Trouble walkers. They cause violence and don't care about anything else than spilling more blood. That's why they are kept outside the city, on the other side of the wall to protect us from them. But it's been 50 years and the wall is in need of repairing, so what keeps us...from them?