This episode opens with another great look into the hubris of the Marines. Captain Morgan quickly identifies the source of Luffy’s power, a devil fruit, and is almost in awe of the strength that such a thing is capable of delivering, seemingly jealously coveting to eat a devil fruit himself, and yet he still rushes headstrong to attack Luffy with supreme confidence that he can defeat a superior rival with his team of Marines. Luffy obviously kills him.
At first, the Marines actually seem embarrassed watching their leader be smacked around, but as the dust settles, they in fact celebrate his defeat, as they are not loyal ideological Marines but actually just local conscripts who have been following orders out of fear of violence or retribution against themselves and their friends and families on the island. Even still, they are real Marines and continue to insist that Luffy and his crew leave as soon as possible, although they grant him some leeway as thanks for getting rid of Captain Morgan. This type of awkward and complicated relationship is truly a deep look into real-world political negotiations and dynamics.
We get a much better look at the person Zoro is in this episode. He has his own high-sighted goal, to be the greatest swordsman in the world, and it is clear that Luffy recognizes this passion and ambition with great respect and is even more excited to add such a passionate member to his crew. There is a very wonderful mutual trust & understanding as both of them want to be the best in the world at something, and they know they have a better chance with each other helping them. What is interesting to me is that Zoro is sort of set up as a pirate hunter, but that actually has very little to do with his true character, and seems to just be his method of learning to be a better swordsman: defeating feared pirates.
Another fantastic parallel between Zoro & Luffy is how ridiculous Zoro’s 3-sword fighting technique looks at first glance, much like how weak & silly Luffy seems at first glance, but both are obviously very effective in battle.
We say goodbye-for-now to Koby in this episode, but, ultimately, his passion to follow his dream also mimics the other 2 characters. Although it seems a tad absurd that a small weak inexperienced individual who spent years serving pirates could rise up and be a mighty Marine, he is still exceptionally committed to trying his best to prove how capable he is. He also repeatedly demonstrates his compassion for others, particularly his friends, which seems to contradict the Marine culture we have seen thus far. Even more interesting is that having seen the corruption and toxicity of the Marines with his own 2 eyes at this point, he still not only wishes to join their ranks but also truly believes that the Marines are a noble & altruistic organization and that Captain Morgan is just a minor exception. I think the final interaction between Luffy & Koby before Luffy & Zoro depart is a fantastic look at the type of people both of them are, with Luffy being able to set aside his own philosophy to help his friend achieve a goal that Luffy thinks is weird & bad, and Koby being willing to do anything to join the Marines, including being assaulted & humiliated by someone he considers a friend.
Final thought, we get some very minor exposition about the Grand Line throughout this episode. Luffy discusses it with the mom who runs the island cafe, but this feels more like folklore than facts, just some things both of them have heard, or are considered sort of common knowledge, but as everyone who has tried to go there has died, I think there is not a realistic way that the average person would have any deep insight into the real truth of the location. However, at the end of the episode, the mysterious eponymous girl who we still haven’t really met is trying to steal a map to the Grand Line from the Marines, finding that some pirates beat her to it, and this seems much more revealing about what it may take to achieve Luffy’s goal: uncommon knowledge and rare information.