Caribou has been an interesting character ever since Fishman Island. So far, Caribou has knowledge of Shirahoshi being one of the ancient weapons, and Pluton being hidden somewhere in Wano. It feels like Oda is very slowly building up Caribou’s role in the One Piece World. What exactly is Caribou going to do with this information, and who is he going to tell it to?
There has been discussion of who exactly is Caribou planning on revealing this information. People have been assuming he is talking about Blackbeard, but for right now I do not really buy that theory. Mostly because Caribou has so far not given any indication of working alongside someone else except his brother.
Also, he has been observed to be a bit too crazy to work alongside with and control since he disobeyed the fake Straw Hats by killing the marine and is obsessed with burying people alive.
Finally, Caribou might realize that Blackbeard could kill him after learning this information since he is a devil fruit hunter. While Caribou is 100% crazy, I do not think he is stupid enough to take a huge risk on whether Blackbeard will kill him or not.
Caribou also does not want anything to do with the World Government, as shown in the recent chapters, as he was upset about being dropped off Egghead Island, making it very unlikely he was planning to reveal this information to the World Government.
I was rereading Fishman Island, and I noticed something. Caribou was capturing regular mermaids to sell them as slaves. When he first saw Shirahoshi, his immediate reaction was to capture her and sell her for money.
Afterward, Caribou tries to attack Pekoms and Tamago for apparently taking the treasure he was planning on stealing. He also goes back to attempting to kidnap regular mermaids after that failed as well.
Taking these events into consideration, it was unlikely Caribou was allied with any big pirates since he would want to tell them first. Based on Caribou’s greedy personality, he is planning on revealing the existence of ancient weapons to someone who can pay him big, which could be Big News Morgan or anyone who is willing to pay a huge amount of money for him.
Caribou doesn’t ally with anyone, he just wants to make money. Caribou knows the location of two ancient weapons, his purpose is to sell this information to someone who is willing to pay a huge amount of money.