"I'm under a fairy curse. The fae are a type of person at home; they have powerful magic and tend to be easily offended, and when my father was a teenager, he offended one, and was cursed to the effect that his pain will never fade. If he'd known he was hereditary, he would never have had children. I was born with half a lifetime of accumulated bumps and scrapes - not the injuries themselves, but their echoes. This scar is inherited." He taps his cheek. "By all accounts I was a deeply unhappy baby. So my mother went on a campaign to be exquisitely polite and helpful to fairies until one agreed to bless her kid - not to undo the curse, they don't do that, but to mitigate it somehow so I would have any hope of ever leading a normal life. It's hard to put into words exactly what my blessing is, but it gives me an effectively unlimited pain tolerance."