Lucius had to chuckle. It was odd - but welcome - to see Severus in such good spirits, much less to wrangle a smile and a compliment out of him. "Thank you for being able to look past the legend that is Lucius Malfoy to see my true character," he said, half-joking; but only half. His ego was inflated enough to truly think of himself as someone so amazing, such the subject of gossip and rumors (hopefully spread by pretty young Witches of noble families) that it would take a particularly studied mind to really understand him, and that mind in this case belonged to Severus Snape.
"It's rather a nice change to see you more... ah... upbeat, I suppose. I hope the train to Hogwarts won't dampen your spirits. Let a few hexes loose for me, will you? Those Prewetts are especially deserving."