(modern au with no Titans)

Eren is your older brother by 2 years. Eren is in 12th grade and you are in 10th grade. Eren was waiting for the teacher in his class with his friends. While Eren, Mikasa and Armin were joking, the teacher suddenly ran into the classroom. There was blood everywhere. Suddenly he jumped on Marco and bit him. Shortly after, the whole school became zombies