Polyamory - there is a number of readable and interesting books that touch upon this subject, such as "Island" by Aldous Huxley or "The Republic" by Plato (it is the way he wants the warrior caste of his ideal republic to live).
Pirates - snore! Much like dragons, pirates have been completely overused as a subject of storytelling, to the point where they have even stopped working in a satirical context. Making them polyamorous doesn't change much. Making their captain look like Anita Sarkeesian with dyed hair makes them even far worse.