One Piece has been running for over 20 years now, and over the course of that tenure series creator Eiichiro Oda has introduced tons and tons of characters to the franchise. What's completely wild about this is that Oda has actually thought up backstories and details about each of these characters that help flesh out his plans for the world of the series but may also never make it to the series at all. One of the key groups in recent years has been Trafalgar D. Water Law and his Heart Pirates, and Oda actually has a whole back story about how this group together.
In a recently resurfaced SBS segment in which Oda answers fan questions with each new volume of the manga, Oda broke down the origins of the Heart Pirates and the members with a pretty significant back story.
After Corazon protected him with his life, Law headed to Swallow Island. On this island he met a young Shachi and Penguin, who were beating up a polar bear. This polar bear was actually Bepo, who left Zou in search of his older brother but soon ended up on Swallow Island too. Shachi and Penguin tried to fight Law, but he soon beat them with ease. This earned the respect of all three of them, who decided to follow Law from then on.
Bepo had been studying navigation and seafaring hoping to return to Zou someday, and with that knowledge, Law, Bepo, Shachi, and Penguin this found the Heart Pirates together. Oda noted in the column that this story won't make its way to the manga, so it's even more impressive that he crafted this origin story all the same. Oda continues to surprise fans with the amount of foreshadowing an attention to detail he puts into the series huge amount of characters, and with the origin of the Heart Pirates he's filled in one big detail that might even come into play someday. It's all on the table with Oda.
Eiichiro Oda's One Piece first began serialization in Shueisha's Weekly Shonen Jump in 1997. It has since been collected into over 80 volumes, and has been a critical and commercial success worldwide with many of the volumes breaking printing records in Japan. The manga has even set a Guinness World Record for the most copies published for the same comic book by a single author, and is the best-selling manga series worldwide with over 430 million copies sold. The series still ranked number one in manga sales in 2018, which surprised fans of major new entries.