I think Lucius is acting fine, he did just possibly lose the girl he was crushing on (Though I still have high hopes for Luzo! XD ), so it is understandable he'd be a little vexed at having to show up at the ball. Plus there was that skirmish the day before where he very nearly died and now he has to rub elbows with some of the people who almost killed him! Maybe his job requires him to be there, but no one said anything about him having to like it.
Besides, different characters are what makes the game fun. If everyone was laughing and happy it'd be boring! ^.^