(He wouldn't be Martel if he weren't an expert in making people intensely dislike his smug ass.)

The wound itself is tinged now with fae magic - magic that had lashed out at him while he was working a far healthier binding into the fabric of Anna's mind, tearing open this old, scarred over injury of mind and sorcery. In effect, it's not one moment but several over the course of a little more than a decade - the stain of the forbidden secrets in the first place, the binding that took him from half-mad to half-mad and in a physically painful despair, the jagged wound where that binding was hacked out of him and replaced with something less kind still-

It's like a back catalogue of every poor decision he's made over the years. It's his history written in his own blood.