@Jabberwok:
Hancock is doing it to protect Amazon Lily, same as Jinbe was. Mihawk is a bit harder to read but I think he's a Shichibukai because it affords him the freedom of movement to seek out promising swordsmen.
you call that ulterior motives, these all come with the territory, all skikabukai has that as a privilage, some use it for island some for nakama ect. Hancock island getting over looked is just part of her deal, jimbei and Weeble same, hawkeyes we know nothing as of yet… would not call that ulterior motives....
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@Katzztar:
Protection for her island, Amazon Lily and its people the Kuja. Back in the ID arc, we learned that if she quit the Shichibukai, the MQ would target her home island. Before the calm belt alone was enough to protect it, but with the battleships having the seastone coating their hulls, they can now travel on the Calm Belt and reach Amazon Lily.
Mihawk? no idea.
still apart from what king cannon said, would like to remind that there have been previous empresses and its not clear if they were all pirates. Handcock is a pirate so of course like doflamingo if he had no connections losing shikabukai status would earn the pirates a navy visit.
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@Jabberwok:
Fair enough, ulterior motives might not be the best term for them. She has motivations beyond simply prestige, a reason why she specifically wants to be a Shichibukai rather than just a famous and powerful pirate.
prestige don't come as a result of becoming a warlord, rather having prestige and being famous and powerful is part of the required resume to be welcomed as….