One scene that is very dear to my heart is when Gwyn rides to the Institute to beg Mark and the others to save Kieran's life after he's found to have killed Iarlath.
It's just sooooo complicated for Mark because I understand he feels betrayed and everyone agrees Kieran's actions caused Julian and Emma a lot of pain. But then again-- that was never Kieran's intention. He genuinely believed Mark's only punishment for his "fault" would be to be dragged back to Faerie, and that's all Kieran wanted-- to have Mark back.
And no other of the kids saw it as that-- as an attempt for Kieran to get his love, the one he'd lost, back, which backfired in a way he just did not know to expect-- but Gwyn did. Gwyn said
"He loved you and he lost you and he tried to get you back,” he said. “He wanted you to ride with the Hunt again. So did I. You were one of our best. Is that so terrible?”
And we know that Kieran regretted it immediately, realized what he'd done, but all he wanted was to have Mark back. And he tried to help, and then he killed Iarlath after getting all that crucial information from him, because he wanted to do what was right. Make up for the mistake he made.
Yes, of course there were meant to be consequences for his actions. Yes, I don't think I would have forgiven him so quickly either, and I don't think Mark was obligated to. But for the punishment to be... death? At the hands of the court?
And Gwyn, leader of the Hunt, possibly the only father figure Kieran ever actually had, to show up at the institute, nearly begging for the shadowhunters to intervene and save him, this kid who is "not yet twenty," saying Where is your compassion?
Because truly. One recurrenr theme in TDA is compassion. We are not defined by our mistakes, just like we shouldn't make vengance our revenge our only purpose. Shadowhunters are best at their mandate when they show mercy. When they care and when they forgive and when they have compassion.
It's like lesson #1 of this entire saga. That's what makes this scene, and Gwyn as a character, so meaningful, so significant. One of my favourite scenes in the whole trilogy for real.