WARNING: The following contains spoilers for One Piece Episode 943, "Luffy's Determination - Win Through the Sumo Inferno!" streaming now on Funimation and Crunchyroll.
Basil Hawkins is one of 12 pirates of the Worst Generation -- a designation he shares with Luffy and Zoro. Introduced in One Piece Episode 392, he's been a recurring adversary throughout the saga. In the Wano Arc, under the leadership of Kaido, Hawkins proved to be particularly dangerous for Luffy and the gang, in part because he's one of the few people who know the Straw Hat Pirates for who they are.
The Straw Hats assumed false identities in order to blend into Wano society. In doing so, they managed to suppress knowledge of their presence for the time being, without Kaido or Orochi realizing that they were confronting some of the mightiest pirates around. However, Hawkins has blown their cover, stripping the masks off of each and every one of the Straw Hats and leaving them vulnerable.
The Oniwabanshu's Plot
As the Straw Hats throw themselves at Orochi and his forces, Hawkins shares his knowledge with Orochi's Oniwabanshu -- a group of elite ninjas, known for information gathering and assassinations. The Oniwabanshu then collect the wanted posters and information of every single member of the Straw Hats, learning their names and value in the eyes of the Navy.
The head of the Oniwabanshu, Fukurokuju, reveals that he knows everything to Zoro by identifying him by his real name. From there, he reveals his intentions to capture at least one Straw Hat in order to torture out information pertaining to their plans in Wano. From there, the two groups fight, though they seem fairly evenly matched when thrown against one another.
Of course, there's an obvious advantage in the Oniwabanshu's court: they already have Luffy in their clutches. While Luffy is all but impossible to torture into submission, should the Oniwabanshu exploit Kaido's hostage, they might be able to get information out of him in theory. Of course, since Luffy has not broken under the pressure of prison life at this point, it's unlikely anything the Oniwabanshu could do would turn him either way. However, Hawkins, again, has found an alternative strategy around that obvious issue.
Trafalgar's Achilles Heel
Hawkins might have already planned for an alternative if the Oniwabanshu fails to capture a Straw Hat pirate. Hawkins has already captured Trafalgar D. Water Law's Heart Pirates. Trafalgar is one of the main pirates involved in the plot against Kaido and Orochi, and Hawkins appears to realize that the Straw Hats and the Heart Pirates are in league with one another.
In this episode, he calls out to Trafalgar, bringing him to an isolated, but open, the area where his pirates are caged up. However, while Law seems to think it will be easy to break his friends free, Hawkins turns the tables by demonstrating how any injury was done unto him will be dealt with his pirates. This puts Trafalgar at a disadvantage since any resistance he displays will end up hurting his companions.
Hawkins might be able to extract even more information from Law, thus establishing him as the man who exposes the plot against his master. That is, of course, unless the arrival of one Charlotte Linlin at Oden Prison doesn't cause even more problems for Kaido.