One Piece has long established its legacy in the world of anime and manga. During its long tenure, its main cast has gone through a lot and changed a good deal. They are extremely different from when they started, and have grown strong enough to contend with the Four Emperors. However, one particular Straw Hat has a more dynamic character development than the rest.
The franchise follows Monkey D. Luffy's adventure. The Pirate King aspirant with questionable intellectual prowess has undergone multiple metamorphoses throughout the series. However, his character development is rather linear and often results in developing a new technique. Luffy's meltdown due to Ace's death is the only exception to that, as it forced him to mature mentally. On the contrary, his sniper's growth has been colorful and complicated, even before the time skip.
From Liar to a Man of Conviction
Usopp was first introduced as a comic relief character. His only good trait was telling tall tales and believable lies, and even that was dubious at times. However, that changed during the events that unfolded in Water 7 and Enies Lobby. Despite being the weakest among the Straw Hats at the time, he challenged Luffy to a duel with the Going Merry at stake. He might have lost to Luffy, but he proved his conviction and gained ownership over his beloved ship. Sanji was the only other Straw Hat who hit Luffy at full force, but he only did that with the intention of saving the crew.
Even after gaining ownership of the Straw Hats' original craft, he wasn't just going to let the Marines abduct one of his nakama. He assumed the identity of Sogeking and fought alongside his former crewmates. However, joining hands against the Marines didn't mean being part of the crew once more. Even though Zoro needed to give him a little push, Usopp realized that Luffy is first and foremost his captain and took the straightforward steps himself to rejoin the Straw Hat Pirates. This makes Usopp the only character to leave the group due to personal reasons and come back after realizing his position. Both Sanji and Robin cut close to this, but ultimately fall short as their reasons for leaving were for the safety of their friends.
From Coward to a Dependable Nakama
Usopp was, and perhaps still is, cowardly. That's why his dream is to become a brave warrior of the sea. True enough, he is slowly realizing that dream. He, alongside Nami and Chopper, was always the first to run in the face of danger, and that was fine given his position as the crew's marksman. However, he decided to step up after catching wind of his captain's loss in Marineford. He trained day and night, immensely improving his strength and physique. All the other Straw Hats are similar in this regard since every one of them decided to improve themselves for the sake of their captain. However, Usopp is a special case.
Unlike Zoro and Sanji, he didn't have monstrous strength or constitution. He was just as a common villager, in terms of physicality. The other members of the cowardly trio, Nami and Chopper, upgraded themselves by acquiring more knowledge. That being said, Usopp's training paid off. He became a more dependable member of the Straw Hat Pirates and even managed to hold his ground against big-time opponents.
Every member of the Straw Hat Pirates has undeniably grown stronger throughout their journey, but Usopp has the most eventful arc. Unlike the others, he struggled with simply trying to figure out his rightful place on the ship. But one thing's for sure: He's a true Straw Hat and one of Luffy's greatest friends.