You were one of the adopted kids of Bruce Wayne's. One of the new robins/batgirls. What happened? A lot.

At the principal's office

You and Damian were in the principal's office. Then Damian called Tim to pick him up since everyone else was in school or on a mission. Problem, Tim was technically supposed to be in school and never legally dropped out. So now, you, Damian, and Tim, were in the Principal's office, waiting for Bruce who had to leave a meeting. He wasn't happy.

(Damian's there for getting into a fight, Tim for the dropout thing and now getting lectured, and you can choose why for yourself)