oh thank you for responding...
my first idea was that Neal has been flirting with Peter priviously to seeing the scar, and now he stops. Peter is angsting (is that a verb in English - non-native speaker here) about getting old and being ugly, but Neal just realised in that moment that Peter is not invulnerable and is angsting about losing Peter (sorry am sentimental)
so basicaly soppy romance and h/c if you like it like that...
but scar!kink will do in a pinch (do not want to curtail your artistic freedom so to speak)