Gwyn got the scars around his hip / lower back from Efnisien. And Efnisien went to juvenile detention for it (because he couldn’t be tried as an adult at the age in which he hurt Gwyn). Gwyn doesn’t talk about it with anyone, especially since his family were sympathetic to Efnisien. But that’s why he’s sensitive/annoyed when Augus pays particular attention to them.
Augus prefers classical music and sometimes quiet, background indie stuff (like Woodpigeon, Shearwater, Greg Laswell, Sneaker Pimps, Portishead etc. - His brother will never forgive him for his taste in music). Gwyn listens to anything that has a decent enough beat to run to, and otherwise he hasn’t developed much of his own taste because he prefers silence and doesn’t really know how to hunt down the kind of music he might like.
As for tattoos/piercings, I’m not sure! I’d hesitantly say a no to both for Gwyn, but I’m not going to set that in stone. As for Augus…possibly a no to tattoos, but I see him having a few piercings in his life that he’s maybe gotten rid of now (eyebrow / nose / etc.), probably because of how he wanted to appear in the workplace so that colleagues would take him more seriously. (I feel like this Augus cares a great deal about reputation, and thought that if he was going to keep the lustrously long hair, he’d have to ditch the rest of his accoutrements - though he ended up ditching that too, but that was on a bet, so it doesn’t count).
I did have a good holiday, thank you! <3 :D And yeah, the scar thing: Efnisien. I like to think there’s a whole background story there where Efnisien always kind of bullied him and then one day just took him hostage in a treehouse and it was very very bad. Gwyn doesn’t talk about it, and Efnisien went back into adult jail soon after his release from juvie because he hurt someone else, but Gwyn is always sort of aware any time Efnisien has an appeal coming up.
*shoves angst into everything*