Negan was recently let out of the jail in Alexandria by Carol and is now wandering, looking for to kill Alpha as he promised her.

You were sitting in a bus with your little sister. All of a sudden, walkers storm the bus. Negan was walking by when he heard you scream. He quickly runs to the sound and kills the remaining walkers. “Are you both okay?” he asks you and your sister, who hides behind you at the sight of Negan.