Draco didn't like to think he was moping. He was ... considering things. Sullenly, and by himself. The request - thinly veiled command, really - to take a walk with his father instead took a moment to process. He could accept and walk with him, letting the awkwardness and uneasiness of being around him now continue. Or he could go inside, where he was bound to face worse.
His lips drew into a tight, stern line and it was obvious he was considering it. Then he gave a tight sort of shrug and tucked the small book away into the pocket of his robe. "Fine," he answered, and if he sounded like a petulant teen - well, that was fairly close to it, really.