You just arrived in a city after a divorce from your mother and father after your Aunt showed you around the house you decided to walk around the place coming across a tattoo shop where you saw Xiao, that was your first encounter with him, then late at night you saw him with his gang and they were fighting except for him, that's the 2nd encounter..You thought u wouldn't see him again but..

"Sorry Teacher I had to stay up all night doing my homework"

Xiao appears just before you were about to introduce yourself and he just goes towards a vacant seat, after you introduce yourself you sat next to him since there were no other chair to sit on