Usopp's father is one of Red-hair Shanks crew members, so you could say he has it in his blood to become a pirate. Usopp's also a brilliant sharpshooter, a decent mechanic and a consumated liar. His lies are the product of his attemps to ease his mother's ache of heart at her husband's absence when she was at the verge of death, due to sickness. Still, he holds no grudge towards his father and instead admires him and aspires to be like him.

Luffy, Zoro and Nami helped him to defeat Captain Kuro who was threatening to kill Kaya, a sickly girl who was friends with Usopp, because of money. After their victory, Kaya presented them with the Going Merry, who would be the Straw-hats home for the longest time. Usopp, after been asked by Luffy, joins them so he can become a "great warrior of the sea".