Despite the cruelty he shows to others, he has immense respect for the Straw Hat Pirates. After witnessing Luffy's miraculous survival on the execution stand in Loguetown two years ago, Bartolomeo became a massive fan of Luffy's and views him as his hero, even to the point of worshipping him.

Is Bartolomeo going to join Luffy?

8 Characters Who Will Join The Straw Hat Grand Fleet (& 7 Who Won't) ... The members of the Grand Fleet swore their loyalty to Luffy and vowed to help him in the time of need. The Straw Hat Grand Fleet currently has seven members: Bartolomeo, Cavendish, Orlumbus, Don Sai, Ideo, Hajrudin, and Leo.

Is Bartolomeo a bad guy?

When Barto is first introduced at Dressrosa it's revealed that he got his high bounty and reputation from his sour attitude and his penchant to kill civilians. But after his initial introduction we find out Barto is a pretty nice guy.