The Seraphim have been giving the Straw Hat Pirates a lot of trouble ever since One Piece’s Egghead Arc started. Besides how tough they can be to fight, they’re constantly changing sides based on who has the highest authority. Currently, they’re working on the orders of a traitor Vegapunk to kill everyone.
The Straw Hats could probably destroy the Seraphim if necessary, but they might not want to. Unlike most Pacifistas they’ve fought in the past, the Seraphim have sentience. Destroying them may come with the same implications as taking a life.
How Human Are the Seraphim?
At first, there were only subtle signs that the Seraphim had their own thoughts and feelings. They would have mild changes to their expressions and even produced word bubbles with ellipses to suggest thought. Both of these things were far from the capabilities of the cold, unthinking machines that the other Pacifistas seemed to be.
Of course, there are some more concrete signs that the Seraphim have humanity. In Chapter 1070, “The Strongest Form of Humanity,” S-Snake was shown getting flustered and defensive when Jimbei paid her a compliment. In Chapter 1073, “Miss Buckingham Stussy,” S-Hawk being pushed back by Zoro caused him to show an intense face complete with forehead veins and sweat drops; if that scene isn’t an ideal metaphor for the moral dilemma surrounding the Seraphim, nothing is. Zoro even noted that S-Hawk seemed more human than the person he was modeled after. Even if they move and act like machines most of the time, they are still alive deep down.
As human as the Seraphim are, however, leaving them alive might be too dangerous. Even if the Straw Hats manage to find the traitor among the Vegapunks and get the Seraphim back under control, St. Jaygarcia Saturn could put them all under his absolute control once he arrives on Egghead. The Straw Hats could stop them again by knocking out Saturn so control defaults to their ally, Stussy, but that would require them to get through Admiral Kizaru and all the warships he’s bringing to Egghead; this would be while the Seraphim are on the attack. At that point, trying to stop the Seraphim without causing too much harm to them could become more trouble than it’s worth.
Could the Egghead Arc End With the Seraphim As Allies?
That said, many fans are assuming the Egghead Arc will end with the Straw Hats fighting Kizaru. If that happens, then they may as well go for Saturn while they’re at it. That way, they could get the Seraphim back on their side while beating the people they would have had to fight sooner or later anyway.
In any case, if it came down to a full-on fight, the Straw Hats would likely aim to knock out the Seraphim rather than destroy them. They might even try to be relatively gentle about it, in case these killing machines do somehow end up on their side one day, be that on Egghead or somewhere else. They may be killing machines, but they have the same rights to life as any other sentient being.