(was too lazy to think of a scenario so I stole from the wiki lol)

Sometime after Yosaku left to inform Luffy of Nami's destination, Usopp, Zoro, and Johnny arrived at the island Nami went to. As they approached the island, they tied up Zoro to keep him from attacking the fish-men, who were fabled to be 10 times stronger than humans. However, they spotted three fish-men as they pulled close to shore. Usopp and Johnny quickly abandoned the ship, leaving Zoro defenseless. While Zoro was brought to Arlong, Usopp stumbled upon another fish-man and was quickly knocked out by a woman. When Usopp woke up in her home, she informed him that Nami was a member of Arlong's crew and had deceived him the entire time.

When he was presented to Arlong, Usopp asked Nami for help. This caused more questions to be raised about Nami's loyalty as she had a similar experience with saving Zoro. Nami attempted to prove her loyalty to the Arlong Pirates by appearing to kill Usopp. From their point of view, she had stabbed Usopp and thrown him into the sea to die. Having escaped Arlong's clutches, Usopp met up with Luffy and his group. Afterwards, Nojiko approached them and explained about Nami's story. Upon seeing Nami's sorrow and fear for her village, the Straw Hats headed for Arlong Park. The Straw Hats faced the fish-men themselves as the villagers watched from the sidelines. While trying to pull Luffy out of the cement, he accidentally knocked over Chew. Frustrated with this, Chew charged after Usopp as he ran away. Chew noticed the townsfolk and considered killing them, only to be set on fire by Usopp. The sniper announced to Chew that he was his opponent, only to run away again.

Usopp spent a long time running, hoping to exhaust Chew, but to no avail. He instead used ketchup and faked being struck down, so Chew turned back towards Arlong Park. Usopp chose living over fighting, and he began to rub himself with dirt to make a convincing argument that he did fight. Remembering how much Luffy, Zoro, Nami, and Sanji risked their lives everyday and how much Nami needed him, Usopp got up and screamed at Chew that the battle was not over.

After receiving powerful punches and kicks, Usopp tricked Chew and hid in a nearby cluster of trees. Chew began to shoot down the trees, and Usopp screamed in fear, accepting that this was the new life he chose. When Chew found him, Usopp set him on fire. He then proceeded to smack Chew in the face with a hammer repeatedly until he fell unconscious.