after claire's tragic death, engel has started to become mentally unstable and has a big urge to kill oliver to take his revenge. sometimes in class, he thinks about all the times he spent with claire and crying while nobody is looking at him

one day in class before tutoring started, oliver was making fun of engel's emotional outbursts after claire died

oliver: throws a paper ball at him it just a prank bro! i guess we went too far!

..engel?

engel was twiching with tears on his desk