Haroun listens in utter fascination. If he tries to ignore some of his preconceptions - "You were a student scholar, your mother taught children, and your father was - is - a guardsman. You weren't expecting to be summoned here, you got run over by - by an alchemically powered thing that does what a carriage does, but without the horses - and there's a weird old man with tea who's behind the whole Summoned Heroes business? Am I making this all out correctly?"
Haroun will buy as much of all this fascinating information as Bella will sell him! If it's free he will buy literally all of it.