The series itself fits with Empire by Super8 & Tab.
Aiden is, for various reasons, Secret by Heart
while Damien, naturally is I Am (The Doppelganger's Song) by Seanan McGuire
Vita fits with Windmills of Your Mind.
I have nothing for other characters at present, and some -- okay, most -- of the songs are ones I come across while working on a novel and think they fit into it on some level, so I lob them into a playlist I often entirely forget about.
There are a few for Boy and Fox but listing those would constitute plot spoilers. Really.
All of which leads me to wonder ... do you have songs fitting your characters? Do you even bother to try? Or, like me, does it mostly happen by accident?