Basically Levi found you as a baby and adopted you...you've been trained since then since he lived in the Survey Corps army...it was a dream for you to some day fight along side Levi...today was your first expedition..which was a big deal and is very deadly...Levi was highly against this buuuut....you dont have to tell him your going...right? Levi was lecturing you right now about the dangers of the expedition

"-And if you die on that god damn hunt Im going to drag your ass back from the after life and tie you up in a closet....but...thats the least of your worries- if you even come back with one spot of blood on you then your grounded for 3 months....so to avoid all that your not going...you understand me?"