Hello there! I'd like to address the issue that is Bartolomeo. The Bart Club captain is not only one of the more predominant and interesting characters of the arc, but he says he has a past with Luffy. This is what I've decided to investigate. I know there has been a lot of talk about his identity, but I think I've found a pretty good guess, one that is better than Bluejam or Sabo.
That is right. Our blood thirsty delinquent is none other than the pompous noble from Luffy and Sabo's childhood.
Let me take the time to explain my reasoning and maybe some of you will soon agree.
Some of you are probably wondering why Stelly of all people would have beef with our Straw Hatted friend. Here is my idea. World Nobles are some twisted dudes and do really anything they want to anyone they want if they have a reason. They would probably even go to destroy the lives of the family of someone who defied them. And that's what Sabo did. If they managed to identify Sabo as Outlook's son, I think they would've ruined there lives. Stripped them of their rank, threw them into the streets, maybe even arrested Outlook and Sabo's mom. That would leave little, bitter, egotistical Stelly, who originally came from a family above Sabo, in the dirt with nothing and no one. If I were him, I would vow to ruin the lives of whoever was responsible. He would probably blame Sabo's desire for piracy, and that would also mean blaming Ace and Luffy. Since Ace his dead and Stelly can't exact his revenge on him, Luffy is the only one left to crush.
There is my idea. Time to provide the evidence in this case.
Here is my proof. And, lemme tell ya, it is in more then just the pudding.
First off, I want to make note of the facial similarities. Both Bart and Stelly have similar shaped noses, long and thin. The bridge stops right between the eyes, which are almost oval shaped. They also have similar looking lips/mouths. You might argue the difference of hair color, but we haven't seen Bart in the anime, and blond hair is pretty easy to dye.
Now to address his attitude. When we saw Stelly, he hated everyone below him and referred to the people of the Gray Terminal as trash. Bartolomeo, as we saw during B Block, was extremely rude and disrespectful to the audience and the other competitors, pissing off the side and practically ignoring Hack. If he happens to be Stelly, this attitude could be explained by the feeling that those without nobility are below him.
This could be the best evidence I have. Think about the Bari Bari no mi for a second. The entire purpose is to keep the user safe from outside forces. Bartolomeo retained not a single scratch from the entire Block. Stelly, with his views of people-trash, wouldn't want to come in contact with anyone below him. He cringed even from Sabo touching him. The idea of a fruit that could not only protect the user from the trash of humanity but also allow him or her to pummel someone below them into the ground without dirtying a finger sound like something that any and all nobles, World or not, would want.
So there is my case. I hope you read and enjoy this theory. Maybe some of you will even agree. I hope so. Adios for now!