Here's my thoughts on some Brook-related possible match-ups and story bits.
Remember that archer who was sniping off anyone who voiced dissent way back during the early years of Orochi's reign of terror? One would think Usopp'd be the logical man for the job to contend with a fellow marksman, but I'd posit that Brook and this guy are fated opponents, though that's not to say Usopp wouldn't play a role.
Exhibit A:
Consider Brook's particularly odd association with arrows: the Rumbar Pirates' death by volley of poisoned arrows; Brook getting launched as a living "lightning arrow" against Oars on Thrillerbark; and just look at all the embedded arrows poking out of his ghostly "disguise" courtesy of Kinemon.
Exhibit B:
Shot in the dark: that dude will be revealed to be a "corrupted" version of a famous hero from Japanese folklore ( one of many ) -- in this case
Fujiwara no Hidesato aka Tawara Toda/My Lord Bag of Rice from the
tale of the same name, famous for slaying a giant centipede using his bow and arrows. Given that villains and heroes usually often take on aspects of the other when adapted to the landscape of One Piece, I'd speculate then that a villainous incarnation would turn out to be a fuson of hero and monster, ie a centipede zoan with some ridiculous archery skills. Hidesato's triumphant fatal shot on the mukade yokai involved him saying a prayer to Japanese gof of war and archery, Hachiman, and licking the arrow prior to landing the killing shot, so picture the evil One Piece version instead doing so to instead coat his arrowheads with poison before firing off a blitz using multiple bows strung with his many centipede arms.
Exhibit C:
Note that Hidesato owes his nickname from a mystical bag of rice he received from the serpent/dragon princess he saved in the story. I mention this because rice, much like salt, is used to ward off and purify evil spirits in Shinto culture. I dunno if that means we'd be seeing Centipede Archer confusing Brook for a ghost and trying to bean him with a bag of rice. Would be hilarious to see Brook and/or Ussop retaliate by attempting to exorcise the "yokai" with a bag of salt haha.
In any case, I see it being relevant and increasing the chances of this playing out, as I'm all but certain we'll be seeing
somebody try "exorcizing" Brook...and succeeding in a way.
Exhibit D:
Note too that Hidesato was a real historical figure who took part in the suppressing one of Japan's most infamous rebels,
Taira no Masakado, a major figure likewise tied to the myth of the Gashadokuro --
a giant skeleton yokai from Japanese folklore; remember that the Oniwabanshu mistook Brook for one at one point. As
another famous legend would have it, Masakado's children would come back for revenge, with his daughter Takiyasha-hime going on to become a demon sorceress who'd summon the giant skeletal monster to combat another famed hero, Oya no Mitsukuni.
Just to further cement these connections
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On that note, we're likely to witness a wild free-for-all ala Marineford and probably more than one major battle ( Soon-to-fail Raid + final climactic battle ), so I'd imagine Brook ( like many ) would have more than opponent to contend with, though each and every confrontation would obviously couldn't lead to a lengthy fight to the finish. S'for that reason I could see him properly engaging Evil Centipede Archer only to hit a wall when pitted up an evil version of Oya no Mitsukuni, who'd defeat Takiyasha-hime's summoned Gashadokuro using his own skill and knowledge of onmyodo sorcery.
I firmly believe the Strawhats are going to go down hard at Onigashima, and it'll partly come down to some of them growing too cocky or careless. In Brook's case, I've a feeling he' s going to dip into the well one too many times with his spooky ghost routine and finally pay dearly for it when someone who knows how to properly deal with "evil spirits" in true Shinto fashion appears. In other words, Brook's either getting "banished" or "sealed" at by somebody whose skill in haki and/or special ability grants them the ability to affect even ghosts.
Whether Brook's downfall comes in the form of some Shinto shrine maiden working for Orochi and Kaido ( there'll be one for sure heading the Golden Kagura ceremony, as is traditional in such bon festivals practices ), some Abe no Seimei cosplayer, or some ersatz Oya no Mtsukuni demon-slayer type, the writing's on the wall either way imo.
Seeing as Basil Hawkins could use a pick-me-up following getting clobbered by Law, maybe he'll get in on the action and help neutralize Brook. The nature of his powers hints at a wide range of applications, so I wouldn't be suprised if he were somehow say seal Brook's soul in a straw doll or something. Perhaps Brook's strawman disguise and his time spent as Big Mom's "doll" is an indication of what's in store?
But yeah, whatever happens, I foresee Brook's spirit somehow being prevented from returning to his body. Much potential for drama and despair if his buddies see his skeleton lying lifeless whilst unsure as to the fate that befell him. Ditto for Brook if he really does get stuck in his immaterial phantom form.
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Wouldn't be permanent, of course. In fact, it might pay off with Brook obtaining a new power. That segues into my next pick -- the Decuplets of the Big Mom Pirates. Granted, always the chance it may not happen this arc, can't even recall if they came along w/ Big Mom, but they're due for some much-needed screen-time, same as Snack, Compote, and Smoothie...so now's as good a time as any.
I think I've already mentioned it already; I predict Brook running into a predicament like the one outlined above, leading him to try and succeed in possessing bones and skeletons other than his own. The Gashadokuro wasn't simply tall, it was a gigantic skeleton, afterall. And like I said, we're bound to get a reference to the popular skeletal whale yokai known as the
bakekujira. So yeah, I think we're going to witness Brook displaying a newfound ability to temporarily possess skeletons other than his own, perhaps even reconfigure his form by rearranging not only his bones but any other he inhabits oradds to his frame. Sorta like Faust from Shaman King, for those familiar.
It's a battle of Skeletal Docking vs Family Docking!