DELPHI
It took me a long time to discover your weakness, Albus Potter. I thought it was pride, I thought it was the need to impress your father, but then I realised your weakness was the same as your father’s – friendship. You will do exactly as you’re told, otherwise Scorpius will die, just like that spare did.

Harry Potter and the Cursed Child - Chapter 3 :
See this quote in the Pensive -