Gladiatorial Battles

You blink slowly, opening your eyes to the bright lights. But when you do, you have no idea where you are. The air smells like sweat, and you scrunch up your nose in disgust. Is this your brother's room? But how did you end up here?
"Hey, look, the newbie's awake!" someone calls, and you hear loud footsteps getting closer and closer to you. Faces swarm your vision, and you can't tell who's who. All you know is that you've never met these people in your life. Something hits your head and you black out.
When you wake up again, the people are gone except for a few, and they're all bruised. They also look sad. What do you do?