'9-1-1': Oliver Stark Talks Sibling Twist and Why Buck's Origin Episode Made Him 'Emotional' (Exclusive)

etonline.com:

Oliver Stark tells ET of when he first heard about the sibling twist., the scars of his childhood resurfacing. «We were on an extended hiatus because of the way of the world, but [showrunner] Tim [Minear] had called me and we had spoken about the possibility of a 'Buck Begins' episode in the past but with the agreement, 'I'll only do it if we find the right story.' So when he called me and he had this idea, I was very excited by it.

Because for me, it's a reveal that makes so much of what we know of Buck fall into place and make sense. And suddenly, we understand why this character that we've come to know over the four seasons is the way he is.