Middlesex!
The facial scar comes from Normandy. Middlesex had become Normandy’s lady-in-waiting/basically slave after her birth a few months after the Norman Conquest, meaning she’s around Normandy 24/7 and ergo around England more than any county, as Normandy is trying to keep the others away, as Normandy was trying to isolate him from the old counties (ie the ones that had been countries prior to the unification of England and the Norman invasion.
So one day, Normandy finds out that Kent, Essex, and the other old ones have been asking Middlesex for information on how England is since they are kept in the dark, and she sees him almost daily. Normandy gets angry and, as a result, claws Middlesex to force her into submitting, which Middlesex soon does, as this attack took the vision in her right eye, which later had to be removed. Normandy then orders Middlesex to tell them the next time the old counties ask if England is happy and safe and loves being under Normandy’s control. Middlesex is terrified for her life, and she does.
So yeah, that's the story of that scar. I am planning out the whole book on the Norman Conquest, but just got such a good mental image of Middlesex that I had to draw and share.