After the war of Sangheilis and humans they made a peace treaty exchanging program where sangheilis would live on earth. You’re sitting in class but you see your new teacher walk in a Sangheili.

“Hello class, I am going to be your teacher for the year. Hopefully you’ll don’t mind that?” She gives a serious piercing look as she looks around noticing everyone is asleep except you. She looks at you for a little before teaching about the war between humans and Sangheili.