Part of the reason I went with Nick was because of how he is right now. He's so happy, so vibrant and so full of life, I felt the tragedy would've been bigger, to cut it down. I liked the idea of using Nick to really take away things he's never done yet (marriage, kids). Not to mention as the youngest, it tapped into the "older brother" feelings of the others. This time they couldn't protect him, this time they couldn't fix it. He had to stand alone while the others supported him and watched.
If it had to be someone other than Nick, I probably would've used Kevin. So that I could take away the one who'd always been there for them. But it was too easy a choice, given his age. I wouldn't have used AJ, it just didn't fit, same with Howie. There's Brian I guess, but with his faith so steadfast I feel like the difficulty wouldn't have been as high.
The other thing is, though this is very much centered on Nick's relationships as everyone, I did use this to focus in on the Frick and Frack relationship. Brian's at the center of all of it. I test that friendship to the end. I've always been such a Nick/Brian girl and so putting that through the ringer was another reason I wanted it specifically to be Nick.