One piece, Luffy has a strong background. Grandpa is a navy and his father is a revolutionary leader. Shan Zhi's background, after the author laid a series of foreshadowing, finally revealed that he was a member of the royal family. As for Sauron's background, the author has never made it clear. He is from the East China Sea and has his own surname. According to the pirate's style, he won't be the second Shan Zhi, and Odero didn't deliberately tell the story of Sauron. So I guess Dassault should be a person with no background.

When we talked about the East China Sea, we talked about Sauron's very short childhood. Under the guidance of Master, he practiced martial arts with Guina, and nothing else happened. If you really want to explore Sauron's background, maybe you can write something with his master, or you can look at Guina's subsequent development. The East China Sea is the least mysterious sea area, from which Luffy and others set out. Sauron was born in this sea area, and his life seems mysterious, but compared with Shan Zhi, it is clear.

Soren had his own surname from the beginning-Rolonoya, which was very common. Before he met Luffy, he traveled alone and was known as a bounty hunter. If Sauron had a background, he wouldn't have been just a bounty hunter in the first place.

Besides, Sauron is a very powerful man. Sauron has a very tough temperament. When he was very weak, he dared to challenge Hawkeye alone. Fortunately, he was finally taught by Hawkeye. His strength is not only the tricks he knows, but also his third-rate skills. His strength is endowed by his personality. If it goes all the way to the later development, he is a grassroots without any background. Without magic fruit and any assistance, he became a swordsman by his own efforts. This setting is also very emotional. So, Sauron doesn't need a background, he can make himself glorious.