Before taking the hunter exam, a close friend of Leorio died from an illness that could have been cured. Despite having access to treatment for himself, Leorio was unable to save his friend due to financial constraints and lack of knowledge. Driven by this experience, he decided to pursue a career in medicine with the goal of helping others who may not be able to afford treatment. To earn money for tuition fees and medical expenses, Leorio chose to take the hunter exam.
Leorio is skilled at negotiating and can persuade shopkeepers to lower prices. Although his tactics may appear harsh or impolite at times, it's clear that he has a kind heart towards his friends. His nen type is Emission as demonstrated during his confrontation with Ging.
Leorios nen type is Emission, as seen during the incident with Ging.