The father-son relationship

Sir Thomas maybe the most principled and reserved character of Mansfield Park but when it comes to his elder son he is no more than a helpless father in front of a spoiled child. He tries to persuade Tom out of his ill habits but none of his efforts bear any fruits. Instead of leaving Tom on his own, Sir Thomas lets him drain Edmund’s fortune despite of his ungrateful attitude.  

“You have robbed Edmund for ten, twenty, thirty years, perhaps for life, of more than half the income, which ought to be his. It may hereafter be in my power, or in yours to procure him better preferment; but it must not be forgotten, that no benefit of that sort would have been beyond his natural claims on us, and that nothing can, in fact, be an equivalent for the certain advantage which he is now obliged to forgo through the urgency of your debts”

Tom Bertrand is the classic construction of a tainted elder son indulged exceedingly in drinking and debts. He is told again and again about the nuisances he creates for his family but he is too selfish to pay heed to any of it.

 “Tom listened with some shame and some sorrow; but escaping as quickly as possible, could soon with cheerful selfishness reflect”

Tom ultimately suffers when he has a near-to-death experience due to excessive drinking. Sir Thomas through out the course of the novel tries to define the path and roles of other characters especially Fanny by being stringent with her while cleaning up the mess his elder son created.