"That is because you are intelligent. There are always ulterior motives. Some are just more altruistic than others. Mr. Flint's friends wish to ensure you have a good time, so you are willing to return to support him. Your female friends wish to enjoy your presence. Misters Malfoy, Nott, and Zabini wish to improve your opinion of them. Lucius wishes to support this by moving you from assigned seats to a more informal seating."