Tranio spends the evening with Lord Drylund, making sure that he introduces the man before he needs to do so himself. Tranio is not a gambler himself, but he will happily have his evening paid for in exchange for flattery and the company.
He starts with the octopus, and gets its name.
He then observes, always drinking less than his host. If Drylund runs the casino, then he might not be as gregarious as he appears. Nevertheless, his company should give Tranio insight into any opportunities or issues aboard ship, and, after all, the man has a pet octopus. This is going to be an enjoyable evening.