If anyone did not notice, besides the cool fight scene, this is a chapter mostly about the concept of inherited will: it starts by Perospero submitting to his captain’s order, although not agreeing with or even understanding it.
It’s another example of how Big Mom Pirates crew is pretty meek and passible under Big Mom’s leadership. Following her own pattern, she believes the Whitebeard Pirates became directionless without their captain. Marco corrects her: he can be a remnant of the Whitebeard’s crew, but he still has his own free will.
This expresses the difference between Big Mom – and probably also Kaido and other members of Rocks Pirates crew – and our protagonists: while the Straw Hats, the Red Scabbards and the Whitebeard Pirates are inheriting the will, they are also following their own wish. They are more influenced and encarning someone spirit than just being stuck by some past resentment or ideology.
Just after we see people running towards others while also being carrying memories of another: Carrot from Pedro, Yamato from Oden and Luffy from the “D.” Clan.
The song by Black Maria is not just to look cool, but also can be read as a metacommentary that allows us to articulate these three characters with the Scabbards fighting Kaido over the roof. She is saying that they all, as Oden’s followers did, will undoubtly catch up with their own destiny and, as the two “lovers”, the long promised meeting that each sought will arrive sooner or later.
The Red Scabbards show us, therefore, what truly means to be a remnant, in the sense proposed by Marco: although they never made an effort to formally learn Oden’s fighting style, they can’t help to imitate him for Kaido’s dismay. They never actually “needed” to be taught Oden’s style, it became ingrained in their minds just by looking up to him so much.
In conclusion, Oda is saying that inheriting someone’s will is not about obeying the orders passed by the dead, but being deeply moved by the memories shared with them. Even as you feel compelled to do something, you are still free. This argument may show up again when we see Blackbeard, that seems to follow a much more deterministic philosophy when acting according to destiny – and also the ideals of the old Rocks Pirates.
A beautifully poetic and deep chapter.
Thank you Oda
*Theory by CaiSant