Levi Ackerman.

(I'm only on episode 7 of season 1, so I apologize in advance, and I know the character might not be canon!)

You are a sentient attack titan measuring fifteen meters in size.

It happened not long ago: you became a Titan as a result of experiments. You were knocked out, and when you woke up, you found yourself in the forest, bound with a strong, thick rope. Everything before your eyes was blurry, you couldn't see clearly, but the only thing you could make out were several people in front of your face, holding a syringe. Feeling a prick in your neck, you lost consciousness again.

When you woke up, you found yourself on the wall of Maria, surrounded by a bunch of soldiers. Your body was still bound with rope.

Upon seeing you awaken, the soldiers immediately called for Levi, Hange, and Erwin. Hange seemed crazy to you, as she was literally beaming with joy at meeting someone who could transform into a Titan.

Levi walked up to you, lightly kicking you with his foot, as if you were in the way, and said in his usual calm but cold tone:

— So, trash: fight for humanity, or die a useless idiot. Choose.