Q pivots on his stool so Lucius can see the back of his head. It's mostly bald, with patches of hair growing sparsely among the scars. It looks very much as if he's been burnt.
Q shrinks in his seat as he listens to Lucius' explanation. "I'm sorry," he says in a small voice, mentally kicking himself for his thoughtlessness. He draws circles on the bar in the condensation from his mug. "I came through the Mirror of Erised," he tells the other man. "I think."